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Topics - Geoffw

1
General Chatty Stuff / Fancy buying a house here?
September 24, 2021, 11:37:48 am
Guatemalan Sinkhole



In 2010, the Guatemala City was hit by the tropical storm called Agatha and this horrifying sinkhole appeared.

The sinkhole's diameter was about 65 feet with the depth being around 300 feet. This looks really scary and what's even scarier is that sinkholes are a frequent occurrence in Guatemala City.
2
Astronomy Group / Preseli Astronomy Group meeting Again
September 23, 2021, 06:26:22 pm
Preseli Astronomy Group
Meet: 1st Tuesday of the montha at 7.00pm
Venue: Letterston Memornial Hall, Station Rd, Letterston, Haverfordwest SA62 5RY

We will be holding our first post covid meeting on Tuesday 5 October at 19.00  as restrictions are still in place we hope to be having an observing session in the car park. If the weather is unfavourable there will be a display of telescopes indoors along with an introduction to amateur astronomy.

This will be a free event and all are welcome to come along, but donations to the group are always welcome, you may bring  your own equipment or borrow the group's scopes.

We will not be asking for any membership subscriptions until we can get the group up and running properly, with regular monthly meetings and a sufficient number of interested people to cover the group's annual costs.
Covid restrictions still apply at Letterston Village Hall, the kitchen facilities are currently closed so sorry no tea or coffee available and face masks must be worn inside the building, hand sanitizer is available on site.
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 550 2021 Sep 19

We're delighted that the Society for Popular Astronomy's free Electronic News Bulletins have gained many hundreds of subscribers since we first issued them more than 23 years ago!

They remain free, but if you are not already a member of the SPA, we hope you will consider joining, and supporting the UK's liveliest astronomical society, with members worldwide. You can easily sign up online. https://www.popastro.com/main_...

And now, here is our latest round-up of news.

PERSEVERENCE COLLECTS FIRST SAMPLES
JPL

NASA's Perseverance rover has completed the collection of the first sample of Martian rock, a core from Jezero Crater slightly thicker than a pencil. The core is now enclosed in an airtight titanium sample tube, making it available for retrieval in the future. Through the Mars Sample Return campaign, NASA and ESA (European Space Agency) are planning a series of future missions to return the rover's sample tubes to Earth for closer study. These samples would be the first set of scientifically identified and selected materials returned to our planet from another. Along with identifying and collecting samples of rock and regolith (broken rock and dust) while searching for signs of ancient microscopic life, Perseverance's mission includes studying the Jezero region to understand the geology and ancient habitability of the area, as well as to characterize the past climate.

RADAR OBSERVES 1,000th NEAR-EARTH ASTEROID
JPL

On Aug. 14, a small near-Earth asteroid (NEA) designated 2021 PJ1 passed our planet at a distance of 1.7 million kilometres. Between 20 and 30 metres wide, the recently discovered asteroid wasn't a threat to Earth. But this asteroid's approach was historic, marking the 1,000th NEA to be observed by planetary radar in just over 50 years. And only seven days later, planetary radar observed the 1,001st such object, but this one was much larger. Since the first radar observation of the asteroid 1566 Icarus in 1968, this powerful technique has been used to observe passing NEAs and comets (collectively known as near-Earth objects, or NEOs). These radar detections improve our knowledge of NEO orbits, providing the data that can extend calculations of future motion by decades to centuries and help definitively predict if an asteroid is going to hit Earth, or if it's just going to pass close by. For example, recent radar measurements of the potentially hazardous asteroid Apophis helped eliminate any possibility of it impacting Earth for the next 100 years. In addition, they can provide scientists with detailed information on physical properties that could be matched only by sending a spacecraft and observing these objects up close. Depending on an asteroid's size and distance, radar can be used to image its surface in intricate detail while also determining its size, shape, spin rate, and whether or not it is accompanied by one or more small moons. In the case of 2021 PJ1, the asteroid was too small and the observing time too short to acquire images. But as the 1,000th NEA detected by planetary radar, the milestone highlights the efforts to study the NEAs that have passed close to Earth.

GEOLOGISTS PROPOSE VESTA THEORY
University of Georgia

The asteroid Vesta is the second largest asteroid in our solar system. With a diameter of about 330 miles, it orbits the Sun between the planets Mars and Jupiter. Asteroids have long played a part in building popular fascination with space. "Marooned off Vesta" was the first story published by American writer Isaac Asimov, the third story he wrote, appearing in the March 1939 issue of the science fiction magazine Amazing Stories. Vesta, like Earth, is composed of rock in its crust and mantle, and it has an iron core. Because of its large size (for an asteroid) and because Vesta has a crust, mantle and core, it is considered a planetesimal. Planetesimals are building blocks out of which planets form. Earth formed by accretion of several such planetesimals. "Vesta was on the way to becoming an Earth-like planet, too, but planet formation stopped along the way there early in the history of our solar system. Vesta was hit by two other large asteroids which left large impact craters so big they cover most of the southern hemisphere of Vesta. These impacts are thought to have ejected rocky material into space. Some of these rocks reached Earth as meteorites so scientists now have actual rock samples from Vesta to study its geochemistry. One big question is what triggered the formation of these large troughs. The two troughs are concentric around the two massive impact basins, Rheasilvia and Veneneia, respectively, and widely considered to be simultaneously formed by the impact events, though this assumed age relationship has never been tested before. The origin of the troughs has long been a point of conjecture within the scientific community.

The leading hypothesis suggests that these troughs are fault-bounded valleys with a distinct scarp on each side that together mark the down-drop (sliding) of a block of rock. However, rock can also crack apart and form such troughs, an origin that has not been considered before. Calculations also show that Vesta's gravity is not enough to induce surrounding stresses favourable for sliding to occur at shallow depths, instead, the physics shows that rocks there are favoured to crack apart. Therefore, the formation of these troughs must involve the opening of cracks, which is inconsistent with the leading hypothesis in the scientific community. Taken all together, the overall project provides alternatives to the previously proposed trough origin and geological history of Vesta, results that are also important for understanding similar landforms on other small planetary bodies elsewhere in the solar system.

OBJECT COLLIDES WITH JUPITER
Spaceweather.com

On the night of September 13-14, German astronomer Harald Paleske was watching the shadow of Io create a solar eclipse in the atmosphere of Jupiter when something unexpected happened. "A bright flash of light surprised me," he says. "It could only be an impact." Paleske video-recorded the event. Reviewing the frames, he quickly ruled out objects such as airplanes and satellites, which might be crossing Jupiter at the time of his observation. The fireball was fixed in Jupiter's atmosphere. It first appeared at 22:39:27 UT on Sept. 13th and remained visible for a full two seconds. The most likely explanation is a small asteroid or comet striking the giant planet; an asteroid in the 100m size range would do the trick. This isn't the first time astronomers have seen things hitting Jupiter. The most famous example is Comet Shoemaker-Levy 9 (SL9), which struck Jupiter in July 1994. At the time, most astronomers thought such collisions were rare, happening every hundred years or so. Since SL9, however, amateur astronomers using improved low-light cameras have observed more than a dozen impact flashes in Jupiter's cloudtops. The Solar System is more dangerous than we thought. Paleske pinpoints the fireball at Jovian latitude 106.9° (CM1), longitude +3.8°. Other observers are encouraged to monitor the location for debris. Previous impacts have sometimes created inky clouds -- probably the remains of the impactor itself mixed with aerosols formed by shock-chemistry during the explosion.

LARGEST STAR EVER DISCOVERED
Cosmos Up

Stars have always been part of civilizations. In Ancient Times, we relied upon the apparent motion of these bodies to navigate distances, to measure the passage of time therefore determining seasons, months, and years. Simply, stars are the very reason we exist. We are literally made up of "stardust". A star, by definition, is an astronomical object consisting mostly of hydrogen and helium all held together by its own gravity. Stars are the most fundamental building blocks of galaxies. So, how many stars are in the Milky Way? Clearly, it is impossible to know exactly how many stars are out there, in all variety of masses and sizes, astronomers estimate that our galaxy alone is made up of approximately 100 billion stars. The most common stars are Red dwarf, which make up the largest population of stars in our galaxy. On the other side of the spectrum are hypergiants, the biggest known stars in the Universe. Since the Gaia data release, scientists have adjusted the distances and therefore the mass of many stars. Prior to the Gaia release, UY Scuti was considered the biggest of these stars, around 1,700 times the Sun's width. Now, we have a new heavyweight champion, an object that defy expectations. Meet Stephenson 2-18.

Stephenson 2-18 is a red supergiant located 19,800 light years away from us in a relatively small cluster called Stephenson 2 in the constellation of Scutum. With an estimated radius about 2,100 times that of the Sun, and a volume nearly 10 billion times of our Sun, Stephenson 2-18 is mind-boggling big, it appears to be considerably larger than the maximum theoretical size of a hypergiant. To put it in perspective, if the centre of our solar system were replaced by Stephenson 2-18, the star's outer atmospheric layer would extend beyond the orbit of Saturn. It would take Earth's fastest plane more than 500 years to travel around. Astronomers predict that Stephenson 2-18 may even continue to grow bigger, possibly one day becoming what is known as a yellow hyper-giant. Just a few million years from now this gigantic glowing ball of plasma may also enter into the latter stages of its life as it quickly burns through its fuel and eventually explodes in a catastrophic, but magnificent supernova, possibly even leaving behind a black hole as a reminder of Stephenson 2-18s once extreme parameters.

COLD PLANETS EVEN EXIST IN THE GALACTIC BULGE
Osaka University

Although thousands of planets have been discovered in the Milky Way, most reside less than a few thousand light years from Earth. Yet our Galaxy is more than 100,000 light years across, making it difficult to investigate the Galactic distribution of planets. But now, a research team has found a way to overcome this hurdle. Scientists have used a combination of observations and modelling to determine how the planet-hosting probability varies with the distance from the Galactic centre. The observations were based on a phenomenon called gravitational microlensing, whereby objects such as planets act as lenses, bending and magnifying the light from distant stars. This effect can be used to detect cold planets similar to Jupiter and Neptune throughout the Milky Way, from the Galactic disk to the Galactic bulge -- the central region of our Galaxy. Gravitational microlensing currently provides the only way to investigate the distribution of planets in the Milky Way, but until now, little is known mainly because of the difficulty in measuring the distance to planets that are more than 10,000 light years from the Sun. To solve this problem, the researchers instead considered the distribution of a quantity that describes the relative motion of the lens and distant light source in planetary microlensing. By comparing the distribution observed in microlensing events with that predicted by a Galactic model, the research team could infer the Galactic distribution of planets. The results show that the planetary distribution is not strongly dependent on the distance from the Galactic centre. Instead, cold planets orbiting far from their stars seem to exist universally in the Milky Way. This includes the Galactic bulge, which has a very different environment to the solar neighbourhood, and where the presence of planets has long been uncertain.

HYDROGEN-BURNING WHITE DWARFS AGE SLOWLY
ESA/Hubble Information Centre

The prevalent view of white dwarfs as inert, slowly cooling stars has been challenged by observations from the Hubble Space Telescope. White dwarfs are the slowly cooling stars which have cast off their outer layers during the last stages of their lives. They are common objects in the cosmos; roughly 98% of all the stars in the Universe will ultimately end up as white dwarfs, including our own Sun. Studying these cooling stages helps astronomers understand not only white dwarfs, but also their earlier stages as well. To investigate the physics underpinning white dwarf evolution, astronomers compared cooling white dwarfs in two massive collections of stars: the globular clusters M3 and M13. These two clusters share many physical properties such as age and metallicity but the populations of stars which will eventually give rise to white dwarfs are different. In particular, the overall colour of stars at an evolutionary stage known as the Horizontal Branch are bluer in M13, indicating a population of hotter stars. This makes M3 and M13 together a perfect natural laboratory in which to test how different populations of white dwarfs cool. Using Hubble's Wide Field Camera 3 the team observed M3 and M13 at near-ultraviolet wavelengths, allowing them to compare more than 700 white dwarfs in the two clusters. They found that M3 contains standard white dwarfs which are simply cooling stellar cores. M13, on the other hand, contains two populations of white dwarfs: standard white dwarfs and those which have managed to hold on to an outer envelope of hydrogen, allowing them to burn for longer and hence cool more slowly.

Comparing their results with computer simulations of stellar evolution in M13, the researchers were able to show that roughly 70% of the white dwarfs in M13 are burning hydrogen on their surfaces, slowing down the rate at which they are cooling. This discovery could have consequences for how astronomers measure the ages of stars in the Milky Way. The evolution of white dwarfs has previously been modelled as a predictable cooling process. This relatively straightforward relationship between age and temperature has led astronomers to use the white dwarf cooling rate as a natural clock to determine the ages of star clusters, particularly globular and open clusters. However, white dwarfs burning hydrogen could cause these age estimates to be inaccurate by as much as 1 billion years.

STELLAR COLLISION TRIGGERS SUPERNOVA
National Radio Astronomy Observatory

Astronomers have found dramatic evidence that a black hole or neutron star spiralled its way into the core of a companion star and caused that companion to explode as a supernova. The astronomers were tipped off by data from the Very Large Array Sky Survey (VLASS), a multi-year project using the National Science Foundation's Karl G. Jansky Very Large Array (VLA). The first clue came when the scientists examined images from VLASS, which began observations in 2017, and found an object brightly emitting radio waves but which had not appeared in an earlier VLA sky survey, called Faint Images of the Radio Sky at Twenty centimeters (FIRST). They made subsequent observations of the object, designated VT 1210+4956, using the VLA and the Keck telescope in Hawaii. They determined that the bright radio emission was coming from the outskirts of a dwarf, star-forming galaxy some 480 million light-years from Earth. They later found that an instrument aboard the International Space Station had detected a burst of X-rays coming from the object in 2014. The data from all these observations allowed the astronomers to piece together the fascinating history of a centuries-long death dance between two massive stars. Like most stars that are much more massive than our Sun, these two were born as a binary pair, closely orbiting each other. One of them was more massive than the other and evolved through its normal, nuclear fusion-powered lifetime more quickly and exploded as a supernova, leaving behind either a black hole or a superdense neutron star. The black hole or neutron star's orbit grew steadily closer to its companion, and about 300 years ago it entered the companion's atmosphere, starting the death dance. At this point, the interaction began spraying gas away from the companion into space. The ejected gas, spiralling outward, formed an expanding, donut-shaped ring, called a torus, around the pair.

Eventually, the black hole or neutron star made its way inward to the companion star's core, disrupting the nuclear fusion producing the energy that kept the core from collapsing of its own gravity. As the core collapsed, it briefly formed a disk of material closely orbiting the intruder and propelled a jet of material outward from the disk at speeds approaching that of light, drilling its way through the star. The collapse of the star's core caused it to explode as a supernova, following its sibling's earlier explosion. The material ejected by the 2014 supernova explosion moved much faster than the material thrown off earlier from the companion star, and by the time VLASS observed the object, the supernova blast was colliding with that material, causing powerful shocks that produced the bright radio emission seen by the VLA. The key to the discovery, Hallinan said, was VLASS, which is imaging the entire sky visible at the VLA's latitude -- about 80 percent of the sky -- three times over seven years. One of the objectives of doing VLASS that way is to discover transient objects, such as supernova explosions, that emit brightly at radio wavelengths. This supernova, caused by a stellar merger, however, was a surprise.

ASTRONOMERS SPOT SAME SUPERNOVA THREE TIMES
University of Copenhagen - Faculty of Science

An enormous amount of gravity from a cluster of distant galaxies causes space to curve so much that light from them is bent and emanated our way from numerous directions. This "gravitational lensing" effect has allowed astronomers to observe the same exploding star in three different places in the heavens. They predict that a fourth image of the same explosion will appear in the sky by 2037. The study provides a unique opportunity to explore not just the supernova itself, but the expansion of our Universe. One of the most fascinating aspects of Einstein's theory of relativity is that gravity is no longer described as a force, but as a "curvature" of space itself. The curvature of space caused by heavy objects does not just cause planets to spin around stars, but can also bend the orbit of light beams. The heaviest of all structures in the Universe -- galaxy clusters made up of hundreds or thousands of galaxies -- can bend light from distant galaxies behind them so much that they appear to be in a completely different place than they actually are. But that's not it: light can take several paths around a galaxy cluster, making it possible for us to get lucky and make two or more sightings of the same galaxy in different places in the sky using a powerful telescope. Some routes around a galaxy cluster are longer than others, and therefore take more time. The slower the route, the stronger the gravity; yet another astonishing consequence of relativity. This staggers the amount of time needed for light to reach us, and thereby the different images that we see. This has allowed a team of astronomers at the Cosmic Dawn Center -- a basic research center run by the Niels Bohr Institute at the University of Copenhagen and DTU Space at the Technical University of Denmark to observe a single galaxy in no less than four different places in the sky. The observations were made using the infrared wavelength range of the Hubble Space Telescope.

By analyzing the Hubble data, researchers noted three bright light sources in a background galaxy that were evident in a previous set of observations from 2016, which disappeared when Hubble revisited the area in 2019. These three sources turned out to be several images of a single star whose life ended in a colossal explosion known as a supernova. The supernova, nicknamed "SN-Requiem," can be seen in three of the four "mirrored images" of the galaxy. Each image presents a different view of the explosive supernova's development. In the final two images, it has not yet exploded. But, by examining how galaxies are distributed within the galaxy cluster and how these images are distorted by curved space, it is actually possible to calculate how "delayed" these images are. This has allowed astronomers to make a remarkable The fourth image of the galaxy is roughly 21 years behind, which should allow us to see the supernova explode one more time, sometime around 2037. Should we get to witness the SN-Requiem explosion again in 2037, it will not only confirm our understanding of gravity, but also help to shed light on another cosmological riddle that has emerged in the last few years, namely the expansion of our Universe. We know that the Universe is expanding, and that different methods allow us to measure by how fast. The problem is that the various measurement methods do not all produce the same result, even when measurement uncertainties are taken into account. Could our observational techniques be flawed, or -- more interestingly -- will we need to revise our understandings of fundamental physics and cosmology? Dark matter and dark energy are the mysterious matter believed to make up 95% of our Universe, whereas we can only see 5%. The perspectives of gravitational lenses are promising!

LARGEST VIRTUAL UNIVERSE FREE FOR ANYONE TO EXPLORE
National Institutes of Natural Sciences

Forget about online games that promise you a "whole world" to explore. An international team of researchers has generated an entire virtual UNIVERSE, and made it freely available on the cloud to everyone. Uchuu (meaning "Outer Space" in Japanese) is the largest and most realistic simulation of the Universe to date. The Uchuu simulation consists of 2.1 trillion particles in a computational cube an unprecedented 9.63 billion light-years to a side. For comparison, that's about three-quarters the distance between Earth and the most distant observed galaxies. Uchuu will allow us to study the evolution of the Universe on a level of both size and detail inconceivable until now. Uchuu focuses on the large-scale structure of the Universe: mysterious halos of dark matter which control not only the formation of galaxies, but also the fate of the entire Universe itself. The scale of these structures ranges from the largest galaxy clusters down to the smallest galaxies. Individual stars and planets aren't resolved, so don't expect to find any alien civilizations in Uchuu. But one way that Uchuu wins big in comparison to other virtual worlds is the time domain; Uchuu simulates the evolution of matter over almost the entire 13.8 billion year history of the Universe from the Big Bang to the present. That is over 30 times longer than the time since animal life first crawled out of the seas on Earth.

An international team of researchers from Japan, Spain, U.S.A., Argentina, Australia, Chile, France, and Italy created Uchuu using ATERUI II, the world's most powerful supercomputer dedicated to astronomy. Even with all this power, it still took a year to produce Uchuu. To produce Uchuu researchers used all 40,200 processors (CPU cores) available exclusively for 48 hours each month. Twenty million supercomputer hours were consumed, and 3 Petabytes of data were generated, the equivalent of 894,784,853 pictures from a 12-megapixel cell phone. The research team used high-performance computational techniques to compress information on the formation and evolution of dark matter haloes in the Uchuu simulation into a 100-terabyte catalogue. This catalogue is now available to everyone on the cloud in an easy to use format thanks to the computational infrastructure skun6 located at the Instituto de Astrofísica de Andalucía (IAA-CSIC), the RedIRIS group, and the Galician Supercomputing Center (CESGA). Future data releases will include catalogues of virtual galaxies and gravitational lensing maps. Big Data science products from Uchuu will help astronomers learn how to interpret Big Data galaxy surveys expected in coming years from facilities like the Subaru Telescope and the ESA Euclid space mission.

Bulletin compiled by Clive Down
(c) 2021 The Society for Popular Astronomy
The Society for Popular Astronomy has been helping beginners in amateur astronomy -- and more experienced observers -- for over 60 years. If you are not a member, you may be missing something. Membership rates are extremely reasonable, starting at just £23 a year in the UK. You will receive our bright bi-monthly magazine Popular Astronomy, help and advice in pursuing your hobby, the chance to hear top astronomers at our regular meetings, and other benefits. The best news is that you can join online right now with a credit or debit card at our lively website: www.popastro.com

4
Family History / Lost Cousin's News
September 13, 2021, 07:54:06 am
We can't bring our ancestors back, but we can keep the memory of them alive....

Plan to map churchyards causes confusion
Conditional baptism
A 19th century midwife
What do you call a male midwife?
Mix-up at the hospital
The other Cromwell
Preserving family heirlooms
Mr & Mrs Selfridge
A medieval place of sanctuary
The Prisoner EXCLUSIVE
The Village
Review: Our Village Ancestors
Peter's Tips

To proceed to the newsletter click the link below (or else, highlight it, copy it, then paste it into your browser).

https://lostcousins.com/newsletters2/sep21news.htm
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 549 2021 Sept 5

JAMES WEBB TELESCOPE TESTED
NASA/STIC

After successful completion of its final tests, NASA's James Webb Space Telescope is being prepped for shipment to its launch site. Engineering teams have completed Webb's long-spanning comprehensive testing regimen at Northrop Grumman's facilities. Webb's many tests and checkpoints were designed to ensure that the world's most complex space science observatory will operate as designed once in space. Now that observatory testing has concluded, shipment operations have begun. This includes all the necessary steps to prepare Webb for a safe journey through the Panama Canal to its launch location in Kourou, French Guiana, on the northeastern coast of South America. Since no more large-scale testing is required, Webb's clean room technicians have shifted their focus from demonstrating it can survive the harsh conditions of launch and work in orbit, to making sure it will safely arrive at the launch pad. Webb's contamination control technicians, transport engineers, and logistics task forces are all expertly prepared to handle the unique task of getting Webb to the launch site. Shipping preparations will be completed in September. While shipment operations are underway, teams at the Space Telescope Science Institute (STScI) in Baltimore will continue to check and recheck the complex communications network it will use in space. Recently this network fully demonstrated that it is capable of seamlessly sending commands to the spacecraft.

Once Webb arrives in French Guiana, launch processing teams will configure the observatory for flight. This involves post-shipment checkouts to ensure the observatory hasn't been damaged during transport, carefully loading the spacecraft's propellant tanks with hydrazine fuel and nitrogen tetroxide oxidizer it will need to power its rocket thrusters to maintain its orbit, and detaching 'remove before flight' red-tag items like protective covers that keep important components safe during assembly, testing, and transport. Then engineering teams will mate the observatory to its launch vehicle, an Ariane 5 rocket provided by ESA (European Space Agency), before it rolls out to the launch pad. Webb is an international program led by NASA with its partners, ESA (European Space Agency) and the Canadian Space Agency. After launch, Webb will undergo a six-month commissioning period. Moments after completing a 26-minute ride aboard the Ariane 5 launch vehicle, the spacecraft will separate from the rocket and its solar array will deploy automatically. After that, all subsequent deployments over the next few weeks will be initiated from ground control located at STScI. Webb will take one month to fly to its intended orbital location in space nearly one million miles away from Earth, slowly unfolding as it goes. Sunshield deployments will begin a few days after launch, and each step can be controlled expertly from the ground, giving Webb's launch full control to circumnavigate any unforeseen issues with deployment. Once the sunshield starts to deploy, the telescope and instruments will enter shade and start to cool over time. Over the ensuing weeks, the mission team will closely monitor the observatory's cooldown, managing it with heaters to control stresses on instruments and structures. In the meantime, the secondary mirror tripod will unfold, the primary mirror will unfold, Webb's instruments will slowly power up, and thruster firings will insert the observatory into a prescribed orbit. Once the observatory has cooled down and stabilized at its frigid operating temperature, several months of alignments to its optics and calibrations of its scientific instruments will occur. Scientific operations are expected to com/mence approximately six months after launch.

WILL IT BE SAFE TO FLY TO MARS?
University of California - Los Angeles

Sending human travellers to Mars would require scientists and engineers to overcome a range of technological and safety obstacles. One of them is the grave risk posed by particle radiation from the Sun, distant stars and galaxies. Answering two key questions would go a long way toward overcoming that hurdle: Would particle radiation pose too grave a threat to human life throughout a round trip to the red planet? And, could the very timing of a mission to Mars help shield astronauts and the spacecraft from the radiation? A team of space scientists answers those two questions with a "no" and a "yes." That is, humans should be able to safely travel to and from Mars, provided that the spacecraft has sufficient shielding and the round trip is shorter than approximately four years. And the timing of a human mission to Mars would indeed make a difference: The scientists determined that the best time for a flight to leave Earth would be when solar activity is at its peak, known as the solar maximum. The scientists' calculations demonstrate that it would be possible to shield a Mars-bound spacecraft from energetic particles from the Sun because, during solar maximum, the most dangerous and energetic particles from distant galaxies are deflected by the enhanced solar activity. A trip of that length would be conceivable. The average flight to Mars takes about nine months, so depending on the timing of launch and available fuel, it is plausible that a human mission could reach the planet and return to Earth in less than two years. The study shows that while space radiation imposes strict limitations on how heavy the spacecraft can be and the time of launch, and it presents technological difficulties for human missions to Mars, such a mission is viable.

The researchers recommend a mission not longer than four years because a longer journey would expose astronauts to a dangerously high amount of radiation during the round trip -- even assuming they went when it was relatively safer than at other times. They also report that the main danger to such a flight would be particles from outside of our solar system. Researchers combined geophysical models of particle radiation for a solar cycle with models for how radiation would affect both human passengers -- including its varying effects on different bodily organs -- and a spacecraft. The modelling determined that having a spacecraft's shell built out of a relatively thick material could help protect astronauts from radiation, but that if the shielding is too thick, it could actually increase the amount of secondary radiation to which they are exposed. The two main types of hazardous radiation in space are solar energetic particles and galactic cosmic rays; the intensity of each depends on solar activity. Galactic cosmic ray activity is lowest within the six to 12 months after the peak of solar activity, while solar energetic particles' intensity is greatest during solar maximum.

INTERSTELLAR COMETS MAY NOT BE RARE
Harvard-Smithsonian Center for Astrophysics

In 2019, astronomers discovered a comet from another star system. Named Borisov, the icy snowball travelled 110,000 miles per hour and marked the first and only interstellar comet ever detected by humans. But what if these interstellar visitors -- comets, meteors, asteroids and other debris from beyond our solar system -- are more common than we think? In a new study, astronomers present new calculations showing that in the Oort Cloud -- a shell of debris in the farthest reaches of our solar system -- interstellar objects outnumber objects belonging to our solar system. The calculations, made using conclusions drawn from Borisov, include significant uncertainties, But even after taking these into consideration, interstellar visitors prevail over objects that are native to the solar system. But if there are so many interstellar visitors, why have we only ever seen one? We just don't have the technology to see them yet. Consider that the Oort Cloud spans a region some 200 billion to 10 trillion miles away from our Sun -- and unlike stars, objects in the Oort Cloud don't produce their own light. Those two factors make debris in the outer solar system incredibly hard to see. These results suggest that the abundances of interstellar and Oort cloud objects are comparable closer to the Sun than Saturn. This can be tested with current and future solar system surveys. When looking at the asteroid data in that region, the question is: are there asteroids that really are interstellar that we just didn't recognize before? Astronomers explain that there are some asteroids that get detected but aren't observed or followed up on year after year. We think they are asteroids, then we lose them without doing a detailed look.

Interstellar objects in the planetary region of the solar system would be rare, but the results clearly show they are more common than solar system material in the dark reaches of the Oort cloud. Observations with next-generation technology may help confirm the team's results. The launch of the Vera C. Rubin Observatory, slated for 2022, will "blow previous searches for interstellar objects out of the water and hopefully help detect many more visitors like Borisov. The Transneptunian Automated Occultation Survey (TAOS II), which is specifically designed to detect comets in the far reaches of our solar system, may also be able to detect one of these passersby. TAOS II may come online as early as this year. The abundance of interstellar objects in the Oort Cloud suggests that much more debris is left over from the formation of planetary systems than previously thought. The findings show that interstellar objects can place interesting constraints on planetary system formation processes, since their implied abundance requires a significant mass of material to be ejected in the form of planetesimals. Together with observational studies of protoplanetary disks and computational approaches to planet formation, the study of interstellar objects could help us unlock the secrets of how our planetary system -- and others -- formed.

UNRAVELLING THE MYSTERY OF BROWN DWARFS
Université de Genève

Brown dwarfs are astronomical objects with masses between those of planets and stars. The question of where exactly the limits of their mass lie remains a matter of debate, especially since their constitution is very similar to that of low-mass stars. So how do we know whether we are dealing with a brown dwarf or a very low mass star? An international team has identified five objects that have masses near the border separating stars and brown dwarfs that could help scientists understand the nature of these mysterious objects. Like Jupiter and other giant gas planets, stars are mainly made of hydrogen and helium. But unlike gas planets, stars are so massive and their gravitational force so powerful that hydrogen atoms fuse to produce helium, releasing huge amounts of energy and light. Brown dwarfs, on the other hand, are not massive enough to fuse hydrogen and therefore cannot produce the enormous amount of light and heat of stars. Instead, they fuse relatively small stores of a heavier atomic version of hydrogen: deuterium. This process is less efficient and the light from brown dwarfs is much weaker than that from stars. This is why scientists often refer to them as 'failed stars'. However, we still do not know exactly where the mass limits of brown dwarfs lie, limits that allow them to be distinguished from low-mass stars that can burn hydrogen for many billions of years, whereas a brown dwarf will have a short burning stage and then a colder life. These limits vary depending on the chemical composition of the brown dwarf, for example, or the way it formed, as well as its initial radius. So far, astronomers have only accurately characterised about 30 brown dwarfs. Compared to the hundreds of planets that astronomers know in detail, this is very few. All the more so if one considers that their larger size makes brown dwarfs easier to detect than planets.

The team characterized five companions that were originally identified with the Transiting Exoplanet Survey Satellite (TESS) as TESS objects of interest (TOI) -- TOI-148, TOI-587, TOI-681, TOI-746 and TOI-1213. These are called 'companions' because they orbit their respective host stars. They do so with periods of 5 to 27 days, have radii between 0.81 and 1.66 times that of Jupiter and are between 77 and 98 times more massive. This places them on the borderline between brown dwarfs and stars. These five new objects therefore contain valuable information. One of the clues the scientists found to show these objects are brown dwarfs is the relationship between their size and age. Brown dwarfs are supposed to shrink over time as they burn up their deuterium reserves and cool down. Here the team found that the two oldest objects, TOI 148 and 746, have a smaller radius, while the two younger companions have larger radii. Yet these objects are so close to the limit that they could just as easily be very low-mass stars, and astronomers are still unsure whether they are brown dwarfs. Even with these additional objects, they still lack the numbers to draw definitive conclusions about the differences between brown dwarfs and low-mass stars.

NEW CLASS OF HABITABLE PLANETS
University of Cambridge

A new class of exoplanet very different to our own, but which could support life, has been identified by astronomers, which could greatly accelerate the search for life outside our Solar System. In the search for life elsewhere, astronomers have mostly looked for planets of a similar size, mass, temperature and atmospheric composition to Earth. However, astronomers from the University of Cambridge believe there are more promising possibilities out there. The researchers have identified a new class of habitable planets, dubbed 'Hycean' planets -- hot, ocean-covered planets with hydrogen-rich atmospheres -- which are more numerous and observable than Earth-like planets.  The researchers say the results could mean that finding biosignatures of life outside our Solar System within the next two or three years is a real possibility. Many of the prime Hycean candidates identified by the researchers are bigger and hotter than Earth, but still have the characteristics to host large oceans that could support microbial life similar to that found in some of Earth's most extreme aquatic environments. These planets also allow for a far wider habitable zone, or 'Goldilocks zone', compared to Earth-like planets. This means that they could still support life even though they lie outside the range where a planet similar to Earth would need to be in order to be habitable. Thousands of planets outside our Solar System have been discovered since the first exoplanet was identified nearly 30 years ago. The vast majority are planets between the sizes of Earth and Neptune and are often referred to as 'super-Earths' or 'mini-Neptunes': they can be predominantly rocky or ice giants with hydrogen-rich atmospheres, or something in between. Most mini-Neptunes are over 1.6 times the size of Earth: smaller than Neptune but too big to have rocky interiors like Earth. Earlier studies of such planets have found that the pressure and temperature beneath their hydrogen-rich atmospheres would be too high to support life. However, a recent study on the mini-Neptune K2-18b found that in certain conditions these planets could support life. The result led to a detailed investigation into the full range of planetary and stellar properties for which these conditions are possible, which known exoplanets may satisfy those conditions, and whether their biosignatures may be observable.

The investigation led the researchers to identify a new class of planets, Hycean planets, with massive planet-wide oceans beneath hydrogen-rich atmospheres. Hycean planets can be up to 2.6 times larger than Earth and have atmospheric temperatures up to nearly 200 degrees Celsius, but their oceanic conditions could be similar to those conducive for microbial life in Earth's oceans. Such planets also include tidally locked 'dark' Hycean worlds that may have habitable conditions only on their permanent night sides, and 'cold' Hycean worlds that receive little radiation from their stars. Planets of this size dominate the known exoplanet population, although they have not been studied in nearly as much detail as super-Earths. Hycean worlds are likely quite common, meaning that the most promising places to look for life elsewhere in the Galaxy may have been hiding in plain sight. However, size alone is not enough to confirm whether a planet is Hycean: other aspects such as mass, temperature and atmospheric properties are required for confirmation. When trying to determine what the conditions are like on a planet many light years away, astronomers first need to determine whether the planet lies in the habitable zone of its star, and then look for molecular signatures to infer the planet's atmospheric and internal structure, which govern the surface conditions, presence of oceans and potential for life. Astronomers also look for certain biosignatures which could indicate the possibility of life. Most often, these are oxygen, ozone, methane and nitrous oxide, which are all present on Earth. There are also a number of other biomarkers, such as methyl chloride and dimethyl sulphide, that are less abundant on Earth but can be promising indicators of life on planets with hydrogen-rich atmospheres where oxygen or ozone may not be as abundant. The team identified a sizeable sample of potential Hycean worlds which are prime candidates for detailed study with next-generation telescopes, such as the James Webb Space Telescope (JWST), which is due to be launched later this year. These planets all orbit red dwarf stars between 35-150 light years away: close by astronomical standards. Planned JWST observations of the most promising candidate, K2-18b, could lead to the detection of one or more biosignature molecules.


ORIGIN OF MILKY WAY'S COSMIC RAYS
Nagoya University

Astronomers have succeeded for the first time in quantifying the proton and electron components of cosmic rays in a supernova remnant. At least 70% of the very-high-energy gamma rays emitted from cosmic rays are due to relativistic protons, according to the novel imaging analysis of radio, X-ray, and gamma-ray radiation. The acceleration site of protons, the main components of cosmic rays, has been a 100-year mystery in modern astrophysics, this is the first time that the amount of cosmic rays being produced in a supernova remnant has been quantitatively shown and is an epoch-making step in the elucidation of the origin of cosmic rays. The origin of cosmic rays, the particles with the highest energy in the Universe, has been a great mystery since their discovery in 1912. Because cosmic rays promote the chemical evolution of interstellar matter, understanding their origin is critical in understanding the evolution of our Galaxy. The cosmic rays are thought to be accelerated by supernova remnants (the after-effects of supernova explosions) in our Galaxy and travelled to the Earth at almost the speed of light. Recent progress in gamma-ray observations has revealed that many supernova remnants emit gamma-rays at teraelectronvolts (TeV) energies. If gamma rays are produced by protons, which are the main component of cosmic rays, then the supernova remnant origin of cosmic rays can be verified. However, gamma rays are also produced by electrons, it is necessary to determine whether the proton or electron origin is dominant, and to measure the ratio of the two contributions. The results of this study provide compelling evidence of gamma rays originating from the proton component, which is the main component of cosmic rays, and clarify that Galactic cosmic rays are produced by supernova remnants.

The originality of this research is that gamma-ray radiation is represented by a linear combination of proton and electron components. Astronomers knew a relation that the intensity of gamma-ray from protons is proportional to the interstellar gas density obtained by radio-line imaging observations. On the other hand, gamma-rays from electrons are also expected to be proportional to X-ray intensity from electrons. Therefore, they expressed the total gamma-ray intensity as the sum of two gamma-ray components, one from the proton origin and the other from the electron origin. This led to a unified understanding of three independent observables. This method was first proposed in this study. As a result, it was shown that gamma rays from protons and electrons account for 70% and 30% of the total gamma-rays, respectively. This is the first time that the two origins have been quantified. The results also demonstrate that gamma rays from protons are dominated in interstellar gas-rich regions, whereas gamma rays from electrons are enhanced in the gas-poor region. This confirms that the two mechanisms work together and supporting the predictions of previous theoretical studies.

HOW YOUNG GALAXIES GROW UP AND MATURE
Lund University

Using a supercomputer simulation, a research team in Sweden has succeeded in following the development of a galaxy over a span of 13.8 billion years. The study shows how, due to interstellar frontal collisions, young and chaotic galaxies over time mature into spiral galaxies such as the Milky Way. Soon after the Big Bang 13.8 billion years ago, the Universe was an unruly place. Galaxies constantly collided. Stars formed at an enormous rate inside gigantic gas clouds. However, after a few billion years of intergalactic chaos, the unruly, embryonic galaxies became more stable and over time matured into well-ordered spiral galaxies. The exact course of these developments has long been a mystery to the world's astronomers. However, in a new study, researchers have been able to provide some clarity on the matter. Astronomers use the Milky Way's stars as a starting point. The stars act as time capsules that divulge secrets about distant epochs and the environment in which they were formed. Their positions, speeds and amounts of various chemical elements can therefore, with the assistance of computer simulations, help us understand how our own galaxy was formed. They have discovered that when two large galaxies collide, a new disc can be created around the old one due to the enormous inflows of star-forming gas. Our simulation shows that the old and new discs slowly merged over a period of several billion years. This is something that not only resulted in a stable spiral galaxy, but also in populations of stars that are similar to those in the Milky Way. The new findings will help astronomers to interpret current and future mappings of the Milky Way. The study points to a new direction for research in which the main focus will be on the interaction between large galaxy collisions and how spiral galaxies' discs are formed. The research team in Lund has already started new super computer simulations in cooperation with the research infrastructure PRACE (Partnership for Advanced Computing in Europe).

NEUTRONS MAY ACTUALLY 'TALK' TO ONE ANOTHER
University of Chicago

Scientists have proposed a new theory that neutrons might communicate under certain circumstances, forming a new sort of 'unparticle'--which could offer evidence of a new kind of symmetry in physics. Even though neutrons love to partner with protons to make the nucleus of an atom, the particles have always been notorious for their reluctance to bind with each other. But according to a new proposed theory, these particles might communicate under certain circumstances, forming a new sort of 'unparticle'--which could offer evidence of a new kind of symmetry in physics.  Dam Thanh Son, the University Professor of Physics at the University of Chicago, laid out the argument in a study published in Proceedings of the National Academy of Sciences, which he co-authored with Hans-Werner Hammer of the Technical University of Darmstadt in Germany. The new study was inspired by an idea first proposed in 2007 by Harvard University professor Howard Georgi, who suggested that there could be a phenomenon beyond our traditional idea of matter. Son and Hammer wanted to try applying this concept to understand the behaviour of particles in the nuclei of atoms--especially more exotic nuclei, which wink in and out existence during violent events in the Universe, such as when stars explode. To study these exotic atomic nuclei on Earth, scientists smash heavy nuclei into each other in accelerators. What comes out is a new nucleus, and a shower of neutrons. Son and Hammer observed that as the neutrons stream out and away, a few that are going in the same direction may continue to "talk" to one another--even after the others have stopped interacting. This sustained communication between neutrons could constitute a fuzzy "unnucleus," with its own properties distinct from normal nuclei.

It's a bit like the difference between being hit by a stone, and being hit by a stream of water. Both carry energy, but the form is different. In their new study, Son and Hammer laid out how and where to look for evidence of these "unnuclei" in accelerators, and a general explanation for the field of what they playfully called "unnuclear physics." This could be a manifestation, the scientists said, of a type of symmetry called conformal symmetry. Symmetries are fundamental to modern physics; they are common features that remain even as a system changes--the most famous being that the speed of light is constant throughout the Universe. In conformal symmetry, a space distorted, but all angles are kept unchanged. For example, when one draws a 2D map of the entire 3D Earth, it is impossible to preserve all distances and angles at the same time. However, some maps, such as a common version first drawn by Gerardus Mercator, are drawn so that all angles remain correct, but at the cost of greatly distorting the distances near the poles. Because the calculations are so robust even if some details are missing, Son said that if the argument is confirmed, physicists might be able to use these formulas to check other calculations. He and Hammer also noted that this behaviour may occur when atoms are cooled to super-low temperatures, and in exotic particles called tetraquarks, made up of two quarks and two antiquarks.

Bulletin compiled by Clive Down

(c) 2021 The Society for Popular Astronomy

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Astronomy Group / The Night Sky in Semtember 2021
September 03, 2021, 12:16:26 pm
The Night Sky in September 2021

September offers stargazers a last chance to see the long, starry arc of the Milky Way and all its attendant splendour. The rich constellations of Scorpius and Sagittarius are moving westward, but the lengthening nights keep these stars accessible for a little longer, at least for observers in the northern hemisphere. In the east, the relatively star-poor constellations of Pegasus, Capricornus, and Piscis Austrinus are moving into view along with hundreds of galaxies accessible with a small telescope. Also, this month, Jupiter and Saturn liven up the southwestern sky, the planet Neptune reaches opposition, and Venus remains low but bright in the west after sunset. Here's what to see in the night sky this month...

CLICK HERE
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JUPITER AND MOONS


SATURN
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Watch on your tablet or PC.  However if you have a smartphone and a VR set try at immersive watch!
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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 547 2021 August 8

We're delighted that the Society for Popular Astronomy's free Electronic News Bulletins have gained many hundreds of subscribers since we first issued them more than 23 years ago!

They remain free, but if you are not already a member of the SPA, we hope you will consider joining, and supporting the UK's liveliest astronomical society, with members worldwide. You can easily sign up online. https://www.popastro.com/main_...

And now, here is our latest round-up of news.


ORIGIN OF CHICXULUB ASTEROID
SOUTHWEST RESEARCH INSTITUTE

The impactor believed to have wiped out the dinosaurs and other life forms on Earth some 66 million years ago likely came from the outer half of the main asteroid belt, a region previously thought to produce few impactors. Researchers have shown that the processes that deliver large asteroids to Earth from that region occur at least 10 times more frequently than previously thought and that the composition of these bodies match what we know of the dinosaur-killing impactor.
The team combined computer models of asteroid evolution with observations of known asteroids to investigate the frequency of so-called Chicxulub events. Over 66 million years ago, a body estimated to be 6 miles across hit in what is now Mexico's Yucatan peninsula and formed Chicxulub crater, which is over 90 miles across. This massive blast triggered a mass extinction event that ended the reign of the dinosaurs. Over the last several decades, much has been learned about the Chicxulub event, but every advance has led to new questions. To probe the Chicxulub impact, geologists have previously examined 66-million-year-old rock samples found on land and within drill cores. The results indicate the impactor was similar to the carbonaceous chondrite class of meteorites, some of the most pristine materials in the solar system. Curiously, while carbonaceous chondrites are common among the many mile-wide bodies that approach the Earth, none today are close to the sizes needed to produce the Chicxulub impact with any kind of reasonable probability. To explain their absence, several past groups have simulated large asteroid and comet breakups in the inner solar system, looking at surges of impacts on Earth with the largest one producing Chicxulub crater. While many of these models had interesting properties, none provided a satisfying match to what we know about asteroids and comets. It seemed like we were still missing something important.

To solve this problem, the team used computer models that track how objects escape the main asteroid belt, a zone of small bodies located between the orbits of Mars and Jupiter. Over eons, thermal forces allow these objects to drift into dynamical "escape hatches" where the gravitational kicks of the planets can push them into orbits nearing Earth. Using NASA's Pleaides Supercomputer, the team followed 130,000 model asteroids evolving in this slow, steady manner for hundreds of millions of years. Particular attention was given to asteroids located in the outer half of the asteroid belt, the part that is furthest from the Sun. To their surprise, they found that 6-mile-wide asteroids from this region strike the Earth at least 10 times more often than previously calculated. This result is intriguing not only because the outer half of the asteroid belt is home to large numbers of carbonaceous chondrite impactors, but also because the team's simulations can, for the first time, reproduce the orbits of large asteroids on the verge of approaching Earth. This explanation for the source of the Chicxulub impactor fits in beautifully with what we already know about how asteroids evolve. Overall, the team found that 6-mile-wide asteroids hit the Earth once every 250 million years on average, a timescale that yields reasonable odds that the Chicxulub crater occurred 66 million years ago. Moreover, nearly half of impacts were from carbonaceous chondrites, a good match with what is known about the Chicxulub impactor. The work will help us better understand the nature of the Chicxulub impact, while also telling us where other large impactors from Earth's deep past might have originated.

MARTIAN DUST STORM ENDED WINTER EARLY IN SOUTH
RAS

A dust storm that engulfed the entire Red Planet in 2018 destroyed a vortex of cold air around the Martian south pole and brought an early spring to the hemisphere. By contrast, the storm caused only minor distortions to the polar vortex in the northern hemisphere and no dramatic seasonal changes. Over two weeks at the beginning of June 2018, localised dust storms combined and spread to form an impenetrable blanket of dust that hid almost the entire planet's surface. The global dust storm, which coincided with Mars's equinox and lasted until mid-September, proved fatal to NASA's solar-powered Opportunity rover. Scientists examined the effects of the event on the Martian atmosphere by combining data from a Mars Global Climate Model with observations from the European Space Agency's ExoMars Trace Gas Orbiter and NASA's Mars Reconnaissance Orbiter missions. It was a perfect opportunity to investigate how global dust storms impact the atmosphere at the Martian poles, which are surrounded by powerful jets of wind in winter. Since the last global storm in 2007, several new missions and instruments have arrived in Mars orbit, so the 2018 event was the most-observed to date.

Previous research has shown that high levels of dust in the atmosphere can have significant effects on polar temperatures and winds. The vortices at the winter poles also affect temperatures and the transport of air, dust, water and chemicals, so their disruption could mean substantial changes in the Martian atmosphere. The team found that the 2018 storm had profoundly different effects in each hemisphere. At the south pole, where the vortex was almost destroyed, temperatures rose and wind speeds fell dramatically. While the vortex may have already been starting to decay due to the onset of spring, the dust storm appears to have had a decisive effect in ending winter early. The northern polar vortex, by contrast, remained stable and the onset of autumn followed its usual pattern. However, the normally elliptical northern vortex was changed by the storm to become more symmetrical. The researchers link this to the high dust content in the atmosphere suppressing atmospheric waves caused by the extreme topography in the northern hemisphere, which has volcanoes over twice as tall as Mount Everest and craters as deep as terrestrial mountains. Global dust storms at equinox may enhance transport into the southern pole due to the diminished vortex, while the more robust northern vortex continues to act as an effective barrier. If this pattern for global dust storms holds over the course of the thousands of years that Mars maintains this particular axial tilt, it has implications for how dust is deposited at the north and south poles and our understanding of the planet's climate history.

EVIDENCE OF WATER VAPOUR ON GANYMEDE
Space Telescope Science Institute (STScI)

For the first time, astronomers have uncovered evidence of water vapour in the atmosphere of Jupiter's moon Ganymede. This water vapour forms when ice from the moon's surface sublimates -- that is, turns from solid to gas. Scientists used new and archival datasets from NASA's Hubble Space Telescope to make the discovery. Previous research has offered circumstantial evidence that Ganymede, the largest moon in the solar system, contains more water than all of Earth's oceans. However, temperatures there are so cold that water on the surface is frozen solid. Ganymede's ocean would reside roughly 100 miles below the crust; therefore, the water vapour would not represent the evaporation of this ocean. In 1998, Hubble's Space Telescope Imaging Spectrograph (STIS) took the first ultraviolet (UV) images of Ganymede, which revealed in two images colourful ribbons of electrified gas called auroral bands, and provided further evidence that Ganymede has a weak magnetic field. The similarities in these UV observations were explained by the presence of molecular oxygen (O2). But some observed features did not match the expected emissions from a pure O2 atmosphere. At the same time, scientists concluded this discrepancy was likely related to higher concentrations of atomic oxygen (O). As part of a large observing program to support NASA's Juno mission in 2018, a team set out to measure the amount of atomic oxygen with Hubble. The team's analysis combined the data from two instruments: Hubble's Cosmic Origins Spectrograph (COS) in 2018 and archival images from the Space Telescope Imaging Spectrograph (STIS) from 1998 to 2010. To their surprise, and contrary to the original interpretations of the data from 1998, they discovered there was hardly any atomic oxygen in Ganymede's atmosphere. This means there must be another explanation for the apparent differences in these UV aurora images.

The team then took a closer look at the relative distribution of the aurora in the UV images. Ganymede's surface temperature varies strongly throughout the day, and around noon near the equator it may become sufficiently warm that the ice surface releases (or sublimates) some small amounts of water molecules. In fact, the perceived differences in the UV images are directly correlated with where water would be expected in the moon's atmosphere. This finding adds anticipation to ESA (European Space Agency)'s upcoming mission, JUICE, which stands for JUpiter ICy moons Explorer. JUICE is the first large-class mission in ESA's Cosmic Vision 2015-2025 program. Planned for launch in 2022 and arrival at Jupiter in 2029, it will spend at least three years making detailed observations of Jupiter and three of its largest moons, with particular emphasis on Ganymede as a planetary body and potential habitat. Ganymede was identified for detailed investigation because it provides a natural laboratory for analysis of the nature, evolution and potential habitability of icy worlds in general, the role it plays within the system of Galilean satellites, and its unique magnetic and plasma interactions with Jupiter and its environment. Right now, NASA's Juno mission is taking a close look at Ganymede and recently released new imagery of the icy moon. Juno has been studying Jupiter and its environment, also known as the Jovian system, since 2016. Understanding the Jovian system and unravelling its history, from its origin to the possible emergence of habitable environments, will provide us with a better understanding of how gas giant planets and their satellites form and evolve. In addition, new insights will hopefully be found on the habitability of Jupiter-like exoplanetary systems.

WHY IS METALLIC STAR HURTLING OUT OF MILKY WAY?
Boston University

About 2,000 light-years away from Earth, there is a star catapulting toward the edge of the Milky Way. This particular star, known as LP 40-365, is one of a unique breed of fast-moving stars -- remnant pieces of massive white dwarf stars -- that have survived in chunks after a gigantic stellar explosion. This star is moving almost two million miles an hour and speeding out of the Milky Way because it's a piece of shrapnel from a past explosion -- a cosmic event known as a supernova -- that's still being propelled forward. To have gone through partial detonation and still survive is unique, and it's only in the last few years that astronomers have started to think this kind of star could exist. Researchers analyzed data from NASA's Hubble Space Telescope and Transiting Exoplanet Survey Satellite (TESS), which surveys the sky and collects light information on stars near and far. By looking at various kinds of light data from both telescopes, the researchers and their collaborators found that LP 40-365 is not only being hurled out of the galaxy, but based on the brightness patterns in the data, is also rotating on its way out. Finding the rotation rate of a star like LP 40-365 after a supernova can lend clues into the original two-star system it came from. It's common in the universe for stars to come in close pairs, including white dwarfs, which are highly dense stars that form toward the end of a star's life. If one white dwarf gives too much mass to the other, the star being dumped on can self-destruct, resulting in a supernova. Supernovas are commonplace in the galaxy and can happen in many different ways, according to the researchers, but they are usually very hard to see. This makes it hard to know which star did the imploding and which star dumped too much mass onto its star partner. Based on LP 40-365's relatively slow rotation rate, astronomers feel more confident that it is shrapnel from the star that self-destructed after being fed too much mass by its partner, when they were once orbiting each other at high speed. Because the stars were orbiting each other so quickly and closely, the explosion slingshotted both stars, and now we only see LP 40-365.

PREVIOUSLY UNSEEN STAR FORMATION IN MILKY WAY
National Radio Astronomy Observatory

Astronomers using two of the world's most powerful radio telescopes have made a detailed and sensitive survey of a large segment of our home galaxy -- the Milky Way -- detecting previously unseen tracers of massive star formation, a process that dominates galactic ecosystems. The scientists combined the capabilities of the National Science Foundation's Karl G. Jansky Very Large Array (VLA) and the 100-meter Effelsberg Telescope in Germany to produce high-quality data that will serve researchers for years to come. Stars with more than about ten times the mass of our Sun are important components of the Galaxy and strongly affect their surroundings. However, understanding how these massive stars are formed has proved challenging for astronomers. In recent years, this problem has been tackled by studying the Milky Way at a variety of wavelengths, including radio and infrared. This new survey, called GLOSTAR (Global view of the Star formation in the Milky Way), was designed to take advantage of the vastly improved capabilities that an upgrade project completed in 2012 gave the VLA to produce previously unobtainable data. GLOSTAR has excited astronomers with new data on the birth and death processes of massive stars, as well on the tenuous material between the stars. The survey detected telltale tracers of the early stages of massive star formation, including compact regions of hydrogen gas ionized by the powerful radiation from young stars, and radio emission from methanol molecules that can pinpoint the location of very young stars still deeply shrouded by the clouds of gas and dust in which they are forming. The survey also found many new remnants of supernova explosions -- the dramatic deaths of massive stars. Previous studies had found fewer than a third of the expected number of supernova remnants in the Milky Way. In the region it studied, GLOSTAR more than doubled the number found using the VLA data alone, with more expected to appear in the Effelsberg data.

The GLOSTAR team combined data from the VLA and the Effelsberg telescope to obtain a complete view of the region they studied. The multi-antenna VLA -- an interferometer -- combines the signals from widely-separated antennas to make images with very high resolution that show small details. However, such a system often cannot also detect large-scale structures. The 100-meter-diameter Effelsberg telescope provided the data on structures larger than those the VLA could detect, making the image complete. Visible light is strongly absorbed by dust, which radio waves can readily penetrate. Radio telescopes are essential to revealing the dust-shrouded regions in which young stars form. The results from GLOSTAR, combined with other radio and infrared surveys, offers astronomers a nearly complete census of massive star-forming clusters at various stages of formation, and this will have lasting value for future studies. GLOSTAR is the first map of the Galactic Plane at radio wavelengths that detects many of the important star formation tracers at high spatial resolution. The detection of atomic and molecular spectral lines is critical to determine the location of star formation and to better understand the structure of the Galaxy.

ROTATING DWARF SPHEROIDAL GALAXIES
Instituto de Astrofísica de Canarias (IAC)

Astrophysicists have discovered the presence of transverse rotation (in the plane of the sky) in three dwarf spheroidal galaxies, a very faint type of galaxies and difficult to observe, which are orbiting round the Milky Way; this helps to trace their evolutionary history. The finding was made using the most recent data from the GAIA satellite of the European Space Agency. Dwarf galaxies have a particular interest for cosmology. The standard cosmological model suggests that this type of galaxies was the first to form. Many of them, the majority, have been destroyed and cannibalized by large galaxies such as the Milky Way. However, those that remain can be studied and contain valuable information about the early Universe. One subclass of dwarf galaxies are the dwarf spheroidals. They are very diffuse, with low luminosity, they contain large proportions of dark matter and little or no gas. Since their discovery they have been deeply studied. However, their internal kinematics are still little known, due to the technical difficulties needed for their detailed study. Various previous studies have shown that the dwarf spheroidals do not have patterns of internal rotation, but their stars move on random orbits predominantly towards and away from the centre of the galaxy. But the galaxies within the other major sub-class of dwarfs, the irregulars, have large quantities of gas, and in some cases do have internal rotation. These differences suggest a different origin for the two types of dwarfs, or to a very different evolutionary history in which interactions with large galaxies, in our case with the Milky Way, have played a crucial role in eliminating the internal rotation of the spheroidals.

To carry out their present research, the team of astrophysicists form the IAC and the STScI have used the latest data from ESA's Gaia to study the internal kinematics of six dwarf spheroidal galaxies, satellites of the Milky Way, and have discovered the presence of transverse rotation (in the plane of the sky) in three of them: Carina, Fornax, and Sculptor. These are the first detections of this type of rotation in dwarf spheroidal galaxies, except for the Sagittarius spheroidal, which is strongly distorted by the gravitational potential of the Milky Way, and is therefore not representative of its type. The importance of this result is because, in general, the internal kinematics of galaxies, in this case their rotation, is an important tracer of their evolutionary history, and of the conditions in which the system was formed. Although the standard model of cosmology assumes that the dwarf galaxies were the first to form, it is not clear if they are simple systems or whether those we observe are formed by the agglomeration of other even simpler systems, smaller and older. The presence of rotation suggests the second option. It also suggests a common origin for all dwarf galaxies, those that are at present rich in gas (the irregulars) and those which are not (the spheroidals). Even so, according to the researchers, studies based on Gaia data entail many technical difficulties. In the first place, one must determine which of the stars in the database really belong to the satellite galaxies, and which to the Milky Way itself, as the latter tend to contaminate the sample. The problem is that although the data to be analysed are limited to the region and the angular size of the spheroidal under study, which is the equivalent of one quarter of the angular diameter of the Moon, the vast majority of the stars detected in this area belong to the Milky Way and therefore indeed contaminate the sample. In addition, the distance of the spheroidals studied, which is up to some half a million light-years, and the low intrinsic luminosity of their stars, imply that the measurements are affected by a considerable level of noise. For all these reasons the analysis of the data requires a thorough filtration and a deep analysis of the different observational parameters to be able to reach reliable conclusions.

REGIONS OF ANDROMEDA WHERE NEW STARS ARE BORN
University of British Columbia

Scientists have published a new, detailed radio image of the Andromeda galaxy -- the Milky Way's sister galaxy -- which will allow them to identify and study the regions of Andromeda where new stars are born. The study is the first to create a radio image of Andromeda at the microwave frequency of 6.6 GHz. Prior to this study, no maps capturing such a large region of the sky around the Andromeda Galaxy had ever been made in the microwave band frequencies between one GHz to 22 GHz. In this range, the galaxy's emission is very faint, making it hard to see its structure. However, it is only in this frequency range that particular features are visible, so having a map at this particular frequency is crucial to understanding which physical processes are happening inside Andromeda. In order to observe Andromeda at this frequency, the researchers required a single-dish radio telescope with a large effective area. For the study, the scientists turned to the Sardinia Radio Telescope, a 64-metre fully steerable telescope capable of operating at high radio frequencies. It took 66 hours of observation with the Sardinia Radio Telescope and consistent data analysis for the researchers to map the galaxy with high sensitivity. They were then able to estimate the rate of star formation within Andromeda, and produce a detailed map that highlighted the disk of the galaxy as the region where new stars are born. For the study, the team developed and implemented software that allowed -- among other things -- to test new algorithms to identify never-before-examined lower emission sources in the field of view around Andromeda at a frequency of 6.6 GHz. From the resulting map, researchers were able to identify a catalogue of about 100 point sources, including stars, galaxies and other objects in the background of Andromeda.

SUPERNOVA'S 'FIZZLED' GAMMA-RAY BURST
NASA/Goddard Space Flight Center

On Aug. 26, 2020, NASA's Fermi Gamma-ray Space Telescope detected a pulse of high-energy radiation that had been racing toward Earth for nearly half the present age of the Universe. Lasting only about a second, it turned out to be one for the record books -- the shortest gamma-ray burst (GRB) caused by the death of a massive star ever seen. GRBs are the most powerful events in the Universe, detectable across billions of light-years. Astronomers classify them as long or short based on whether the event lasts for more or less than two seconds. They observe long bursts in association with the demise of massive stars, while short bursts have been linked to a different scenario. The burst is named GRB 200826A, after the date it occurred. When a star much more massive than the Sun runs out of fuel, its core suddenly collapses and forms a black hole. As matter swirls toward the black hole, some of it escapes in the form of two powerful jets that rush outward at almost the speed of light in opposite directions. Astronomers only detect a GRB when one of these jets happens to point almost directly toward Earth. Each jet drills through the star, producing a pulse of gamma rays -- the highest-energy form of light -- that can last up to minutes. Following the burst, the disrupted star then rapidly expands as a supernova.

Short GRBs, on the other hand, form when pairs of compact objects -- such as neutron stars, which also form during stellar collapse -- spiral inward over billions of years and collide. Fermi observations recently helped show that, in nearby galaxies, giant flares from isolated, supermagnetized neutron stars also masquerade as short GRBs. GRB 200826A was a sharp blast of high-energy emission lasting just 0.65 second. After travelling for eons through the expanding Universe, the signal had stretched out to about one second long when it was detected by Fermi's Gamma-ray Burst Monitor. The event also appeared in instruments aboard NASA's Wind mission, which orbits a point between Earth and the Sun located about 1.5 million kilometres away, and Mars Odyssey, which has been orbiting the Red Planet since 2001. ESA's (the European Space Agency's) INTEGRAL satellite observed the blast as well.
All of these missions participate in a GRB-locating system called the InterPlanetary Network (IPN), for which the Fermi project provides all U.S. funding. Because the burst reaches each detector at slightly different times, any pair of them can be used to help narrow down where in the sky it occurred. About 17 hours after the GRB, the IPN narrowed its location to a relatively small patch of the sky in the constellation Andromeda. Using the National Science Foundation-funded Zwicky Transient Facility (ZTF) at Palomar Observatory, the team scanned the sky for changes in visible light that could be linked to the GRB's fading afterglow. Within a day of the burst, NASA's Neil Gehrels Swift Observatory discovered fading X-ray emission from this same location. A couple of days later, variable radio emission was detected by the National Radio Astronomy Observatory's Karl Jansky Very Large Array in New Mexico. The team then began observing the afterglow with a variety of ground-based facilities. Observing the faint galaxy associated with the burst using the Gran Telescopio Canarias, a 10.4-meter telescope at the Roque de los Muchachos Observatory on La Palma in Spain's Canary Islands, the team showed that its light takes 6.6 billion years to reach us. That's 48% of the Universe's current age of 13.8 billion years. But to prove this short burst came from a collapsing star, the researchers also needed to catch the emerging supernova. To conduct the search, the team was granted time on the 8.1-meter Gemini North telescope in Hawaii and the use of a sensitive instrument called the Gemini Multi-Object Spectrograph. The astronomers imaged the host galaxy in red and infrared light starting 28 days after the burst, repeating the search 45 and 80 days after the event. They detected a near-infrared source -- the supernova -- in the first set of observations that could not be seen in later ones. The researchers suspect that this burst was powered by jets that barely emerged from the star before they shut down, instead of the more typical case where long-lasting jets break out of the star and travel considerable distances from it. If the black hole had fired off weaker jets, or if the star was much larger when it began its collapse, there might not have been a GRB at all. The discovery helps resolve a long-standing puzzle. While long GRBs must be coupled to supernovae, astronomers detect far greater numbers of supernovae than they do long GRBs. This discrepancy persists even after accounting for the fact that GRB jets must tip nearly into our line of sight for astronomers to detect them at all. The researchers conclude that collapsing stars producing short GRBs must be marginal cases whose light-speed jets teeter on the brink of success or failure, a conclusion consistent with the notion that most massive stars die without producing jets and GRBs at all. More broadly, this result clearly demonstrates that a burst's duration alone does not uniquely indicate its origin.

DETECTION OF LIGHT FROM BEHIND A BLACK HOLE
Stanford University

Watching X-rays flung out into the Universe by the supermassive black hole at the centre of a galaxy 800 million light-years away, an astrophysicist noticed an intriguing pattern. He observed a series of bright flares of X-rays -- exciting, but not unprecedented -- and then, the telescopes recorded something unexpected: additional flashes of X-rays that were smaller, later and of different "colours" than the bright flares. According to theory, these luminous echoes were consistent with X-rays reflected from behind the black hole -- but even a basic understanding of black holes tells us that is a strange place for light to come from. Any light that goes into that black hole doesn't come out, so we shouldn't be able to see anything that's behind the black hole. It is another strange characteristic of the black hole, however, that makes this observation possible. The reason we can see that is because that black hole is warping space, bending light and twisting magnetic fields around itself. The strange discovery is the first direct observation of light from behind a black hole -- a scenario that was predicted by Einstein's theory of general relativity but never confirmed, until now. Fifty years ago, when astrophysicists starting speculating about how the magnetic field might behave close to a black hole, they had no idea that one day we might have the techniques to observe this directly and see Einstein's general theory of relativity in action. The original motivation behind this research was to learn more about a mysterious feature of certain black holes, called a corona. Material falling into a supermassive black hole powers the brightest continuous sources of light in the universe, and as it does so, forms a corona around the black hole. This light -- which is X-ray light -- can be analyzed to map and characterize a black hole.

The leading theory for what a corona is starts with gas sliding into the black hole where it superheats to millions of degrees. At that temperature, electrons separate from atoms, creating a magnetized plasma. Caught up in the powerful spin of the black hole, the magnetic field arcs so high above the black hole, and twirls about itself so much, that it eventually breaks altogether -- a situation so reminiscent of what happens around our own Sun that it borrowed the name "corona." This magnetic field getting tied up and then snapping close to the black hole heats everything around it and produces these high energy electrons that then go on to produce the X-rays. As researchers took a closer look to investigate the origin of the flares, they saw a series of smaller flashes. These, the researchers determined, are the same X-ray flares but reflected from the back of the disk -- a first glimpse at the far side of a black hole. The mission to characterize and understand coronas continues and will require more observation. Part of that future will be the European Space Agency's X-ray observatory, Athena (Advanced Telescope for High-ENergy Astrophysics).

LOW-COST BALLOON TELESCOPE TO RIVAL HUBBLE
Royal Astronomical Society

Durham, Toronto and Princeton Universities have teamed up with NASA and the Canadian Space Agency to build a new kind of astronomical telescope. SuperBIT flies above 99.5% of the Earth's atmosphere, carried by a helium balloon the size of a football stadium. The telescope will make its operational debut next April and when deployed should obtain high-resolution images rivalling those of the Hubble Space Telescope. Light from a distant galaxy can travel for billions of years to reach our telescopes. In the final fraction of a second, the light has to pass through the Earth's swirling, turbulent atmosphere. Our view of the Universe becomes blurred. Observatories on the ground are built at high altitude sites to overcome some of this, but until now only placing a telescope in space escapes the effect of the atmosphere. The Superpressure Balloon-borne Imaging Telescope (or SuperBIT) has a 0.5 metre diameter mirror and is carried to 40km altitude by a helium balloon with a volume of 532,000 cubic metres, about the size of a football stadium. Its final test flight in 2019 demonstrated extraordinary pointing stability, with variation of less than one thirty-six thousandth of a degree for more than an hour. This should enable a telescope to obtain images as sharp as those from the Hubble Space Telescope. Nobody has done this before, not only because it is exceedingly difficult, but also because balloons could stay aloft for only a few nights: too short for an ambitious experiment. However, NASA recently developed 'superpressure' balloons able to contain helium for months. SuperBIT is scheduled to launch on the next long duration balloon, from Wanaka, New Zealand, in April. Carried by seasonally stable winds, it will circumnavigate the Earth several times -- imaging the sky all night, then using solar panels to recharge its batteries during the day.
With a budget for construction and operation for the first telescope of £3.62 million, SuperBIT cost almost 1000 times less than a similar satellite. Not only are balloons cheaper than rocket fuel, but the ability to return the payload to Earth and relaunch it means that its design has been tweaked and improved over several test flights. Satellites must work first time, so typically have (phenomenally expensive) redundancy, and decade-old technology that had to be space-qualified by the previous mission. Modern digital cameras improve every year -- so the development team bought the cutting-edge camera for SuperBIT's latest test flight a few weeks before launch. This space telescope will continue to be upgradable, or have new instruments on every future flight. In the longer term, the Hubble Space Telescope will not be repaired again when it inevitably fails. For 20 years after that, ESA/NASA missions will enable imaging only at infrared wavelengths (like the James Webb Space Telescope due to launch this autumn), or a single optical band (like the Euclid observatory due to launch next year). By then SuperBIT will be the only facility in the world capable of high-resolution multicolour optical and ultraviolet observations. The team already has funding to design an upgrade from SuperBIT's 0.5 metre aperture telescope to 1.5 metres (the maximum carrying capacity of the balloon is a telescope with a mirror about 2 metres across). Boosting light gathering power tenfold, combined with its wider angle lens and more megapixels, will make this larger instrument even better than Hubble. The cheap cost even makes it possible to have a fleet of space telescopes offering time to astronomers around the world. The science goal for the 2022 flight is to measure the properties of dark matter particles. Although dark matter is invisible, astronomers map the way it bends rays of light, a technique known as gravitational lensing. SuperBIT will test whether dark matter slows down during collisions. No particle colliders on Earth can accelerate dark matter, but this is a key signature predicted by theories that might explain recent observations of weirdly behaving muons.



Bulletin compiled by Clive Down

(c) 2021 The Society for Popular Astronomy

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Astronomy Group / The Night Sky in August 2021
August 04, 2021, 12:42:55 pm
The Night Sky in August 2021



t's an extra good month for stargazing! Both Jupiter and Saturn reach opposition in August and make their best
apparitions of the year. The grand Perseid meteor shower peaks under nearly moonless conditions, ideal for some
summer stargazing under the Milky Way. Venus hangs low and bright over the north-western horizon after sunset,
and tiny Mercury makes a very close approach to Mars on the 18th in the same part of the sky. Early risers get to see
a slender crescent Moon tangled in the stars of the Pleiades and Hyades star clusters in the pre-dawn sky. Here's
what to see in the night sky this month.

CLICK HERE  The Night Sky in August 2021.pdf
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Local Artists Exhibition
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Astronomy Group / Beautiful Video of Jupiter
July 30, 2021, 11:03:24 am
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General Chatty Stuff / Beijing Hotel Brochure
July 26, 2021, 01:11:11 pm
I know this has been around for a while but it still makes me chuckle!

image_2021-07-26_121028.png
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Virgin Galactic launch 2.00pm BST 11th July

"We are at the vanguard of a new industry determined to pioneer twenty-first century spacecraft, which will open space to everybody -- and change the world for good."

- Sir Richard Branson, Founder, Virgin Galactic


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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 545 2021 July 11

We're delighted that the Society for Popular Astronomy's free Electronic News Bulletins have gained many hundreds of subscribers since we first issued them more than 23 years ago!

They remain free, but if you are not already a member of the SPA, we hope you will consider joining, and supporting the UK's liveliest astronomical society, with members worldwide. You can easily sign up online. https://www.popastro.com/main_...

And now, here is our latest round-up of news.

DISCOVERY OF GIANT COMET
Spaceweather.com

Astronomers have discovered a comet so big, it might actually be a minor planet. The object is named 2014 UN271. Astronomers Pedro Bernardinelli and Gary Bernstein found it in archival images from the Dark Energy Survey. It appears to be about 100 km wide, 2 or 3 times bigger than record-breaking Comet Hale-Bopp of the 1990s. Although 2014 UN271 is falling toward the Sun, we may never see it with our naked eyes. At closest approach in early 2031, the behemoth comet will be just outside the orbit of Saturn, too far for naked-eye viewing. Some astronomers are estimating a maximum brightness near magnitude +17, about the same as Pluto's moon Charon. 2014 UN271 has an extremely elongated orbit stretching from ~the neighbourhood of Saturn out to a distance of almost a light year. At the far reaches of its orbit, 2014 UN271 barely feels the Sun's gravity and could be snatched out of the Solar System altogether by the ephemeral pull of galactic tides. Discovering such a traveller during its brief time among the planets is very lucky indeed. There is talk of a space mission to intercept 2014 UN271. The European Space Agency is building a probe called Comet Interceptor designed to investigate comets coming from deep space. It, or something like it, might be able to visit 2014 UN271 a decade from now. With an object like this, we have to expect surprises. 2014 UN271 certainly poses no threat to Earth, but it could brighten more (or less) than expected. Multiple groups of astronomers have already detected signs of out-gassing even though 2014 UN271 is still beyond Uranus. Early signs of activity may bode well for future visibility through small telescopes if not the unaided eye.

METHANE PLUMES ON SATURN'S MOON ENCELADUS
University of Arizona

Giant water plumes erupting from Enceladus have long fascinated scientists and the public alike, inspiring research and speculation about the vast ocean that is believed to be sandwiched between the moon's rocky core and its icy shell. Flying through the plumes and sampling their chemical makeup, the Cassini spacecraft detected a relatively high concentration of certain molecules associated with hydrothermal vents on the bottom of Earth's oceans, specifically dihydrogen, methane and carbon dioxide. The amount of methane found in the plumes was particularly unexpected. Researchers applied new mathematical models that combine geochemistry and microbial ecology to analyze Cassini plume data and model the possible processes that would best explain the observations. They conclude that Cassini's data are consistent either with microbial hydrothermal vent activity, or with processes that don't involve life forms but are different from the ones known to occur on Earth. On Earth, hydrothermal activity occurs when cold seawater seeps into the ocean floor, circulates through the underlying rock and passes close by a heat source, such as a magma chamber, before spewing out into the water again through hydrothermal vents. On Earth, methane can be produced through hydrothermal activity, but at a slow rate. Most of the production is due to microorganisms that harness the chemical disequilibrium of hydrothermally produced dihydrogen as a source of energy, and produce methane from carbon dioxide in a process called methanogenesis. The team looked at Enceladus' plume composition as the end result of several chemical and physical processes taking place in the moon's interior. First, the researchers assessed what hydrothermal production of dihydrogen would best fit Cassini's observations, and whether this production could provide enough "food" to sustain a population of Earthlike hydrogenotrophic methanogens. To do that, they developed a model for the population dynamics of a hypothetical hydrogenotrophic methanogen, whose thermal and energetic niche was modelled after known strains from Earth.

The authors then ran the model to see whether a given set of chemical conditions, such as the dihydrogen concentration in the hydrothermal fluid, and temperature would provide a suitable environment for these microbes to grow. They also looked at what effect a hypothetical microbe population would have on its environment -- for example, on the escape rates of dihydrogen and methane in the plume. The results suggest that even the highest possible estimate of abiotic methane production -- or methane production without biological aid -- based on known hydrothermal chemistry is far from sufficient to explain the methane concentration measured in the plumes. Adding biological methanogenesis to the mix, however, could produce enough methane to match Cassini's observations. For example, methane could come from the chemical breakdown of primordial organic matter that may be present in Enceladus' core and that could be partially turned into dihydrogen, methane and carbon dioxide through the hydrothermal process. This hypothesis is very plausible if it turns out that Enceladus formed through the accretion of organic-rich material supplied by comets.

EARTH-LIKE BIOSPHERES MAY BE RARE
RAS

A new analysis of known exoplanets has revealed that Earth-like conditions on potentially habitable planets may be much rarer than previously thought. The work focuses on the conditions required for oxygen-based photosynthesis to develop on a planet, which would enable complex biospheres of the type found on Earth. The number of confirmed planets in our own Milky Way galaxy now numbers into the thousands. However planets that are both Earth-like and in the habitable zone - the region around a star where the temperature is just right for liquid water to exist on the surface - are much less common. At the moment, only a handful of such rocky and potentially habitable exoplanets are known. However the new research indicates that none of these has the theoretical conditions to sustain an Earth-like biosphere by means of 'oxygenic' photosynthesis - the mechanism plants on Earth use to convert light and carbon dioxide into oxygen and nutrients. Only one of those planets comes close to receiving the stellar radiation necessary to sustain a large biosphere: Kepler−442b, a rocky planet about twice the mass of the Earth, orbiting a moderately hot star around 1,200 light years away. The study looked in detail at how much energy is received by a planet from its host star, and whether living organisms would be able to efficiently produce nutrients and molecular oxygen, both essential elements for complex life as we know it, via normal oxygenic photosynthesis. By calculating the amount of photosynthetically active radiation (PAR) that a planet receives from its star, the team discovered that stars around half the temperature of our Sun cannot sustain Earth-like biospheres because they do not provide enough energy in the correct wavelength range. Oxygenic photosynthesis would still be possible, but such planets could not sustain a rich biosphere.

Planets around even cooler stars known as red dwarfs, which smoulder at roughly a third of our Sun's temperature, could not receive enough energy to even activate photosynthesis. Stars that are hotter than our Sun are much brighter, and emit up to ten times more radiation in the necessary range for effective photosynthesis than red dwarfs, however generally do not live long enough for complex life to evolve. Since red dwarfs are by far the most common type of star in our galaxy, this result indicates that Earth-like conditions on other planets may be much less common than we might hope. The study puts strong constraints on the parameter space for complex life, so unfortunately it appears that the "sweet spot" for hosting a rich Earth-like biosphere is not so wide.

EVIDENCE FOR POPULATION OF FREE-FLOATING PLANETS
RAS

Tantalising evidence has been uncovered for a mysterious population of "free-floating" planets, planets that may be alone in deep space, unbound to any host star. The results include four new discoveries that are consistent with planets of similar masses to Earth. The study used data obtained in 2016 during the K2 mission phase of NASA's Kepler Space Telescope. During this two-month campaign, Kepler monitored a crowded field of millions of stars near the centre of our Galaxy every 30 minutes in order to find rare gravitational microlensing events. The study team found 27 short-duration candidate microlensing signals that varied over timescales of between an hour and 10 days. Many of these had been previously seen in data obtained simultaneously from the ground. However, the four shortest events are new discoveries that are consistent with planets of similar masses to Earth. These new events do not show an accompanying longer signal that might be expected from a host star, suggesting that these new events may be free-floating planets. Such planets may perhaps have originally formed around a host star before being ejected by the gravitational tug of other, heavier planets in the system. Predicted by Albert Einstein 85 years ago as a consequence of his General Theory of Relativity, microlensing describes how the light from a background star can be temporarily magnified by the presence of other stars in the foreground. This produces a short burst in brightness that can last from hours to a few days. Roughly one out of every million stars in our Galaxy is visibly affected by microlensing at any given time, but only a few percent of these are expected to be caused by planets.

Kepler was not designed to find planets using microlensing, nor to study the extremely dense star fields of the inner Galaxy. This meant that new data reduction techniques had to be developed to look for signals within the Kepler dataset. These signals are extremely difficult to find. Astronomers pointed an elderly, ailing telescope with blurred vision at one the most densely crowded parts of the sky, where there are already thousands of bright stars that vary in brightness, and thousands of asteroids that skim across the field. From that cacophony, astronomers try to extract tiny, characteristic brightenings caused by planets, and they only have one chance to see a signal before it's gone. It's about as easy as looking for the single blink of a firefly in the middle of a motorway, using only a handheld phone. Kepler has achieved what it was never designed to do, in providing further tentative evidence for the existence of a population of Earth-mass, free-floating planets. Now it passes the baton on to other missions that will be designed to find such signals, signals so elusive that Einstein himself thought that they were unlikely ever to be observed. Confirming the existence and nature of free-floating planets will be a major focus for upcoming missions such as the NASA Nancy Grace Roman Space Telescope, and possibly the ESA Euclid mission, both of which will be optimised to look for microlensing signals.

EXOPLANETS IN 2,034 STAR SYSTEMS COULD SEE EARTH
Cornell University

Scientists have identified 2,034 nearby star-systems -- within the cosmic distance of 326 light-years -- that could find Earth merely by watching our pale blue dot cross our Sun. That's 1,715 star-systems that could have spotted Earth since human civilization blossomed about 5,000 years ago, and 319 more star-systems that will be added over the next 5,000 years. Exoplanets around these nearby stars have a cosmic front-row seat to see if Earth holds life. Of the 2,034 star-systems passing through the Earth Transit Zone over the 10,000-year period examined, 117 objects lie within about 100 light-years of the Sun and 75 of these objects have been in the Earth Transit Zone since commercial radio stations on Earth began broadcasting into space about a century ago. Included in the catalogue of 2,034 star-systems are seven known to host exoplanets. Each one of these worlds has had or will have an opportunity to detect Earth, just as Earth's scientists have found thousands of worlds orbiting other stars through the transit technique. By watching distant exoplanets transit -- or cross -- their own Sun, Earth's astronomers can interpret the atmospheres backlit by that Sun. If exoplanets hold intelligent life, they can observe Earth backlit by the Sun and see our atmosphere's chemical signatures of life.

The Ross 128 system, with a red dwarf host star located in the Virgo constellation, is about 11 light-years away and is the second-closest system with an Earth-size exoplanet (about 1.8 times the size of our planet). Any inhabitants of this exoworld could have seen Earth transit our own Sun for 2,158 years, starting about 3,057 years ago; they lost their vantage point about 900 years ago. The Trappist-1 system, at 45 light-years from Earth, hosts seven transiting Earth-size planets -- four of them in the temperate, habitable zone of that star. While we have discovered the exoplanets around Trappist-1, they won't be able to spot us until their motion takes them into the Earth Transit Zone in 1,642 years. Potential Trappist-1 system observers will remain in the cosmic Earth transit stadium seats for 2,371 years. Analysis shows that even the closest stars generally spend more than 1,000 years at a vantage point where they can see Earth transit. If we assume the reverse to be true, that provides a healthy timeline for nominal civilizations to identify Earth as an interesting planet. The Breakthrough Starshot initiative is an ambitious project underway that is looking to launch a nano-sized spacecraft toward the closest exoplanet detected around Proxima Centauri -- 4.2 light-years from us -- and fully characterize that world. One might imagine that worlds beyond Earth that have already detected us, are making the same plans for our planet and solar system. This catalogue is an intriguing thought experiment for which one of our neighbours might be able to find us.

WHITE DWARF IS SO MASSIVE IT MIGHT COLLAPSE
W. M. Keck Observatory

Astronomers have discovered the smallest and most massive white dwarf ever seen. The smouldering cinder, which formed when two less massive white dwarfs merged, is heavy, packing a mass greater than that of our Sun into a body about the size of our Moon. It may seem counterintuitive, but smaller white dwarfs happen to be more massive. This is due to the fact that white dwarfs lack the nuclear burning that keep up normal stars against their own self gravity, and their size is instead regulated by quantum mechanics. The discovery was made by the Zwicky Transient Facility, or ZTF, which operates at Caltech's Palomar Observatory; two Hawai'i telescopes -- W. M. Keck Observatory on Maunakea, Hawai'i Island and University of Hawai'i Institute for Astronomy's Pan-STARRS (Panoramic Survey Telescope and Rapid Response System) on Haleakala, Maui -- helped characterize the dead star, along with the 200-inch Hale Telescope at Palomar, the European Gaia space observatory, and NASA's Neil Gehrels Swift Observatory. White dwarfs are the collapsed remnants of stars that were once about eight times the mass of our Sun or lighter. Our Sun, for example, after it first puffs up into a red giant in about 5 billion years, will ultimately slough off its outer layers and shrink down into a compact white dwarf. About 97 percent of all stars become white dwarfs. While our Sun is alone in space without a stellar partner, many stars orbit around each other in pairs. The stars grow old together, and if they are both less than eight solar-masses, they will both evolve into white dwarfs. The new discovery provides an example of what can happen after this phase. The pair of white dwarfs, which spiral around each other, lose energy in the form of gravitational waves and ultimately merge. If the dead stars are massive enough, they explode in what is called a type Ia supernova. But if they are below a certain mass threshold, they combine together into a new white dwarf that is heavier than either progenitor star. This process of merging boosts the magnetic field of that star and speeds up its rotation compared to that of the progenitors.

Astronomers say that the newfound tiny white dwarf, named ZTF J1901+1458, took the latter route of evolution; its progenitors merged and produced a white dwarf 1.35 times the mass of our Sun. The white dwarf has an extreme magnetic field almost 1 billion times stronger than our Sun's and whips around on its axis at a frenzied pace of one revolution every seven minutes (the zippiest white dwarf known, called EPIC 228939929, rotates every 5.3 minutes. What's more, astronomers think that the merged white dwarf may be massive enough to evolve into a neutron-rich dead star, or neutron star, which typically forms when a star much more massive than our Sun explodes in a supernova. If this neutron star formation hypothesis is correct, it may mean that a significant portion of other neutron stars take shape in this way. The newfound object's close proximity (about 130 light-years away) and its young age (about 100 million years old or less) indicate that similar objects may occur more commonly in our galaxy. Data from Swift, which observes ultraviolet light, helped nail down the size and mass of the white dwarf. With a diameter of 2,670 miles, ZTF J1901+1458 secures the title for the smallest known white dwarf, edging out previous record holders, RE J0317-853 and WD 1832+089, which each have diameters of about 3,100 miles.

SPLIT IN LOCAL COSMOS
Washington University in St. Louis

In 2011, scientists confirmed a suspicion: There was a split in the local cosmos. Samples of the solar wind brought back to Earth by the Genesis mission definitively determined oxygen isotopes in the sun differ from those found on Earth, the moon and the other planets and satellites in the solar system. Early in the solar system's history, material that would later coalesce into planets had been hit with a hefty dose of ultraviolet light, which can explain this difference. Where did it come from? Two theories emerged: Either the ultraviolet light came from our then-young Sun, or it came from a large nearby star in the Sun's stellar nursery. Now, researchers have determined which was responsible for the split. It was most likely light from a long-dead massive star that left this impression on the rocky bodies of the solar system. All of that profundity was packed into a mere 85 grams of rock, a piece of an asteroid found as a meteorite in Algeria in 1990, named Acfer 094. Asteroids and planets formed from the same presolar material, but they've been influenced by different natural processes. The rocky building blocks that coalesced to form asteroids and planets were broken up and battered; vaporized and recombined; and compressed and heated. But the asteroid that Acfer 094 came from managed to survive for 4.6 billion years mostly unscathed. Acfer 094 is also the only meteorite that contains cosmic symplectite, an intergrowth of iron-oxide and iron-sulphide with extremely heavy oxygen isotopes -- a significant finding. The Sun contains about 6% more of the lightest oxygen isotope compared with the rest of the solar system. That can be explained by ultraviolet light shining on the solar system's building blocks, selectively breaking apart carbon monoxide gas into its constituent atoms. That process also creates a reservoir of much heavier oxygen isotopes. Until cosmic symplectite, however, no one had found this heavy isotope signature in samples of solar system materials. With only three isotopes, however, simply finding the heavy oxygen isotopes wasn't enough to answer the question of the origin of the light. Different ultraviolet spectra could have created the same result.

That's when the team came up with the idea of sulphur isotopes. Sulphur's four isotopes would leave their marks in different ratios depending on the spectrum of ultraviolet light that irradiated hydrogen sulphide gas in the proto-solar system. A massive star and a young sun-like star have different ultraviolet spectra. Cosmic symplectite formed when ices on the asteroid melted and reacted with small pieces of iron-nickel metal. In addition to oxygen, cosmic symplectite contains sulphur in iron sulphide. If its oxygen witnessed this ancient astrophysical process -- which led to the heavy oxygen isotopes -- perhaps its sulphur did, too. Sulphur and oxygen isotope measurements of cosmic symplectite in Acfer 094 proved another challenge. The grains, tens of micrometers in size and a mixture of minerals, required new techniques on two different in-situ secondary-ion mass spectrometers. The sulphur isotope measurements of cosmic symplectite were consistent with ultraviolet irradiation from a massive star, but did not fit the UV spectrum from the young Sun. The results give a unique perspective on the astrophysical environment of the Sun's birth 4.6 billion years ago. Neighbouring massive stars were likely close enough that their light affected the solar system's formation. Such a nearby massive star in the night sky would appear brighter than the full Moon. Today, we can look to the skies and see a similar origin story play out elsewhere in the galaxy. We see nascent planetary systems, called proplyds, in the Orion nebula that are being photoevaporated by ultraviolet light from nearby massive O and B stars. If the proplyds are too close to these stars, they can be torn apart, and planets never form. We now know our own solar system at its birth was close enough to be affected by the light of these stars. But thankfully, not too close.

THE GOLDILOCKS SUPERNOVA
University of California - Santa Barbara

Scientists have discovered the first convincing evidence for a new type of stellar explosion -- an electron-capture supernova. While they have been theorized for 40 years, real-world examples have been elusive. They are thought to arise from the explosions of massive super-asymptotic giant branch (SAGB) stars, for which there has also been scant evidence. The discovery also sheds new light on the thousand-year mystery of the supernova from A.D. 1054 that was visible all over the world in the daytime, before eventually becoming the Crab Nebula. Historically, supernovae have fallen into two main types: thermonuclear and iron-core collapse. A thermonuclear supernova is the explosion of a white dwarf star after it gains matter in a binary star system. These white dwarfs are the dense cores of ash that remain after a low-mass star (one up to about 8 times the mass of the Sun) reaches the end of its life. An iron core-collapse supernova occurs when a massive star -- one more than about 10 times the mass of the Sun -- runs out of nuclear fuel and its iron core collapses, creating a black hole or neutron star. Between these two main types of supernovae are electron-capture supernovae. These stars stop fusion when their cores are made of oxygen, neon and magnesium; they aren't massive enough to create iron. While gravity is always trying to crush a star, what keeps most stars from collapsing is either ongoing fusion or, in cores where fusion has stopped, the fact that you can't pack the atoms any tighter. In an electron capture supernova, some of the electrons in the oxygen-neon-magnesium core get smashed into their atomic nuclei in a process called electron capture. This removal of electrons causes the core of the star to buckle under its own weight and collapse, resulting in an electron-capture supernova. If the star had been slightly heavier, the core elements could have fused to create heavier elements, prolonging its life. So it is a kind of reverse Goldilocks situation: The star isn't light enough to escape its core collapsing, nor is it heavy enough to prolong its life and die later via different means. Over the decades, theorists have formulated predictions of what to look for in an electron-capture supernova and their SAGB star progenitors. The stars should have a lot of mass, lose much of it before exploding, and this mass near the dying star should be of an unusual chemical composition. Then the electron-capture supernova should be weak, have little radioactive fallout, and have neutron-rich elements in the core.

The new study involved a team of scientists using dozens of telescopes around and above the globe. The team found that the supernova SN 2018zd had many unusual characteristics, some of which were seen for the first time in a supernova. It helped that the supernova was relatively nearby -- only 31 million light-years away -- in the galaxy NGC 2146. This allowed the team to examine archival images taken by the Hubble Space Telescope prior to the explosion and to detect the likely progenitor star before it exploded. The observations were consistent with another recently identified SAGB star in the Milky Way, but inconsistent with models of red supergiants, the progenitors of normal iron core-collapse supernovae. The authors looked through all published data on supernovae, and found that while some had a few of the indicators predicted for electron-capture supernovae, only SN 2018zd had all six: an apparent SAGB progenitor, strong pre-supernova mass loss, an unusual stellar chemical composition, a weak explosion, little radioactivity and a neutron-rich core. The new discoveries also illuminate some mysteries of the most famous supernova of the past. In A.D. 1054 a supernova happened in the Milky Way Galaxy that, according to Chinese and Japanese records, was so bright that it could be seen in the daytime for 23 days, and at night for nearly two years. The resulting remnant, the Crab Nebula, has been studied in great detail. The Crab Nebula was previously the best candidate for an electron-capture supernova, but its status was uncertain partly because the explosion happened nearly a thousand years ago. The new result increases the confidence that the historic SN 1054 was an electron-capture supernova. It also explains why that supernova was relatively bright compared to the models: Its luminosity was probably artificially enhanced by the supernova ejecta colliding with material cast off by the progenitor star as was seen in SN 2018zd.

FIRST DETECTION OF BLACK HOLE-NEUTRON STAR MERGERS
Northwestern University

A long time ago, in two galaxies about 900 million light-years away, two black holes each gobbled up their neutron star companions, triggering gravitational waves that finally hit Earth in January 2020. Discovered by an international team of astrophysicists, two events -- detected just 10 days apart -- mark the first-ever detection of a black hole merging with a neutron star. The findings will enable researchers to draw the first conclusions about the origins of these rare binary systems and how often they merge. Gravitational waves have allowed us to detect collisions of pairs of black holes and pairs of neutron stars, but the mixed collision of a black hole with a neutron star has been the elusive missing piece of the family picture of compact object mergers. Completing this picture is crucial to constraining the host of astrophysical models of compact object formation and binary evolution. Inherent to these models are their predictions of the rates that black holes and neutron stars merge amongst themselves. With these detections, we finally have measurements of the merger rates across all three categories of compact binary mergers. The team observed the two new gravitational-wave events -- dubbed GW200105 and GW200115 -- on Jan. 5, 2020, and Jan. 15, 2020, during the second half of the LIGO and Virgo detectors third observing run, called O3b. Although multiple observatories carried out several follow-up observations, none observed light from either event, consistent with the measured masses and distances. All three large detectors (both LIGO instruments and the Virgo instrument) detected GW200115, which resulted from the merger of a 6-solar mass black hole with a 1.5-solar mass neutron star, roughly 1 billion light-years from Earth. With observations of the three widely separated detectors on Earth, the direction to the waves' origin can be determined to a part of the sky equivalent to the area covered by 2,900 full Moons. Just 10 days earlier, LIGO detected a strong signal from GW200105, using just one detector while the other was temporarily offline.

Virgo also was observing, the signal was too quiet in its data for Virgo to help detect it. From the gravitational waves, the astronomers inferred that the signal was caused by a 9-solar mass black hole colliding with a 1.9-solar mass compact object, which they ultimately concluded was a neutron star. This merger happened at a distance of about 900 million light-years from Earth. Because the signal was strong in only one detector, the astronomers could not precisely determine the direction of the waves' origin. Although the signal was too quiet for Virgo to confirm its detection, its data did help narrow down the source's potential location to about 17% of the entire sky, which is equivalent to the area covered by 34,000 full moons. Because the two events are the first confident observations of gravitational waves from black holes merging with neutron stars, the researchers now can estimate how often such events happen in the universe. Although not all events are detectable, the researchers expect roughly one such merger per month happens within a distance of one billion light-years. While it is unclear where these binary systems form, astronomers identified three likely cosmic origins: stellar binary systems, dense stellar environments including young star clusters, and the centers of galaxies. The team is currently preparing the detectors for a fourth observation run, to begin in summer 2022.

UNDERSTANDING THE ORIGINS OF MATTER IN THE MILKY WAY
University of Maryland Baltimore County

New findings suggest that carbon, oxygen, and hydrogen cosmic rays travel through the galaxy toward Earth in a similar way, but, surprisingly, that iron arrives at Earth differently. Learning more about how cosmic rays move through the galaxy helps address a fundamental, lingering question in astrophysics: How is matter generated and distributed across the Universe? Cosmic rays are atomic nuclei -- atoms stripped of their electrons -- that are constantly whizzing through space at nearly the speed of light. They enter Earth's atmosphere at extremely high energies. Information about these cosmic rays can give scientists clues about where they came from in the galaxy and what kind of event generated them. An instrument on the International Space Station (ISS) called the Calorimetric Electron Telescope (CALET) has been collecting data about cosmic rays since 2015. The data include details such as how many and what kinds of atoms are arriving, and how much energy they're arriving with. Cosmic rays arrive at Earth from elsewhere in the galaxy at a huge range of energies -- anywhere from 1 billion volts to 100 billion billion volts. The CALET instrument is one of extremely few in space that is able to deliver fine detail about the cosmic rays it detects. A graph called a cosmic ray spectrum shows how many cosmic rays are arriving at the detector at each energy level. The spectra for carbon, oxygen, and hydrogen cosmic rays are very similar, but the key finding from the new paper is that the spectrum for iron is significantly different. There are several possibilities to explain the differences between iron and the three lighter elements. The cosmic rays could accelerate and travel through the galaxy differently, although scientists generally believe they understand the latter.

An instrument like CALET is important for answering questions about how cosmic rays accelerate and travel, and where they come from. Instruments on the ground or balloons flown high in Earth's atmosphere were the main source of cosmic ray data in the past. But by the time cosmic rays reach those instruments, they have already interacted with Earth's atmosphere and broken down into secondary particles. With Earth-based instruments, it is nearly impossible to identify precisely how many primary cosmic rays and which elements are arriving, plus their energies. But CALET, being on the ISS above the atmosphere, can measure the particles directly and distinguish individual elements precisely. Iron is a particularly useful element to analyse. On their way to Earth, cosmic rays can break down into secondary particles, and it can be hard to distinguish between original particles ejected from a source (like a supernova) and secondary particles. That complicates deductions about where the particles originally came from. Measuring cosmic rays gives scientists a unique view into high-energy processes happening far, far away. The cosmic rays arriving at CALET represent "the stuff we're made of. We are made of stardust. The latest finding creates more questions than it answers, emphasizing that there is still more to learn about how matter is generated and moves around the galaxy.

OBSERVATIONS OF DISTANT GALAXIES CLOSE IN ON COSMIC DAWN
RAS

New observations of six of the most distant galaxies currently known have helped to pinpoint the moment of first light in the Universe, known as 'cosmic dawn'. Today our Universe is full of light, however this was not the case until the first stars and galaxies formed. The new work narrows down the moment when the Universe was first bathed in starlight to a small window just a few hundred million years after the Big Bang. Prior to this the Universe was a dark place, with dust and gas gradually collecting via gravity to eventually form these first stars and galaxies, bringing to an end the cosmic Dark Ages. The UK-led research team examined the ages of stars contained in six galaxies seen when the Universe was 550 million years old. Detailed observations of the average ages of the stars in each galaxy were made with the world's most powerful ground- and space-based telescopes. These new observations have pushed the earliest period of star formation back to well beyond the horizon accessible with current telescopes. However the team also predicts that the next generation of telescopes, such as the James Webb Space Telescope (JWST), due for launch later this year, will have the sensitivity to directly probe these earliest epochs of the Universe.

RUSSIA LAUNCHING NEW ISS MODULE
ARS Technica

The Russian space corporation, Roscosmos has released photos showing the much-anticipated Nauka space station module enclosed in its payload fairing. This will be Russia's first significant addition to the International Space Station in more than a decade, and it will provide the Russians with their first module dedicated primarily to research. "Nauka" means science in Russian. This is a sizable module, including crew quarters, an airlock for scientific experiments, and much more. With a mass of about 24 metric tons, it is about 20 percent larger than the biggest Russian segment of the station, the Zvezda service module. The timing for this launch, scheduled for as early as July 15 on a Proton rocket, is notable. For one, the multi-purpose Nauka module is more than a dozen years late due to a lack of budget for the project on top of technical issues. At times, it seemed like the module was never actually going to launch. Additionally, Russia is launching its largest module at a time when its future participation in the International Space Station program is uncertain. Russian officials have said the existing hardware on orbit, much of which is more than two decades old, is aging beyond repair. The Russians have said they may pull out of the program in 2025 and build a brand-new station.

So why launch a new module just a few years before exiting the station? One possibility is that the Russians are simply posturing. Some NASA officials have speculated privately that this may be an angle to obtain new funds from the United States. With the success of SpaceX's Crew Dragon vehicle and nearing availability of Boeing's Starliner, NASA is no longer annually sending hundreds of millions of dollars to Roscosmos to purchase Soyuz seats for access to the station. This was an important source of funding for Russia's space program. However, NASA would like to keep the station flying for another decade, and for this it needs the Russians. The first elements of the International Space Station were launched in 1998, and it was designed such that the US and Russian segments were dependent upon one another for attitude control, power, and other critical resources. The NASA officials suspect Russia may seek "maintenance" funding from the United States in return for keeping its part of the space station going. Nauka's launch is an important symbolic win for Russia's space program, in that it is increasingly rare for Roscosmos to develop and fly new hardware. Mostly, the program maintains and launches decades-old spacecraft such as the Soyuz vehicle and the Proton rocket. After being encapsulated in its payload fairing, Nauka will now move to a "filling station" at the Baikonur Cosmodrome in Kazakhstan, where it will be fuelled and pressurized. After that, it will be mated to its Proton rocket for a launch.  

Bulletin compiled by Clive Down

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By Sid PerkinsJun. 4, 2021 , 5:15 PM

When continental plates smashed together about 12 million years ago, they didn't just raise new mountains in central Europe--they created the largest lake the world has ever known. This vast body of water--the Paratethys Sea--came to host species found nowhere else, including the world's smallest whales. Two new studies reveal how the ancient body of water took shape and how surrounding changes helped give rise to elephants, giraffes, and other large mammals that wander the planet today.

TO READ THE FULL ARTICLE CLICK HERE
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..........to our garden this afternoon, and the sad demise of a young blackbird we were getting to know!

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THE SOCIETY FOR POPULAR ASTRONOMY Electronic News Bulletin No. 544 2021 June 27

We're delighted that the Society for Popular Astronomy's free Electronic News Bulletins have gained many hundreds of subscribers since we first issued them more than 23 years ago!

They remain free, but if you are not already a member of the SPA, we hope you will consider joining, and supporting the UK's liveliest astronomical society, with members worldwide. You can easily sign up online. https://www.popastro.com/main_...


And now, here is our latest round-up of news.

ASTEROID 16 PSYCHE MIGHT NOT BE WHAT WE EXPECTED
University of Arizona

The widely studied metallic asteroid known as 16 Psyche was long thought to be the exposed iron core of a small planet that failed to form during the earliest days of the solar system. But new research suggests that the asteroid might not be as metallic or dense as once thought, and hints at a much different origin story. Scientists are interested in 16 Psyche because if its presumed origins are true, it would provide an opportunity to study an exposed planetary core up close. NASA is scheduled to launch its Psyche mission in 2022 and arrive at the asteroid in 2026. New research proposes 16 Psyche is 82.5% metal, 7% low-iron pyroxene and 10.5% carbonaceous chondrite that was likely delivered by impacts from other asteroids. It is estimated that 16 Psyche's bulk density -- also known as porosity, which refers to how much empty space is found within its body -- is around 35%. These estimates differ from past analyses of 16 Psyche's composition that led researchers to estimate it could contain as much as 95% metal and be much denser. Rather than being an intact exposed core of an early planet, it might actually be closer to a rubble pile, similar to another thoroughly studied asteroid - Bennu. A sample from Bennu's surface is now making its way back to Earth. Asteroid 16 Psyche is about the size of Massachusetts, and scientists estimate it contains about 1% of all asteroid belt material. First spotted by an Italian astronomer in 1852, it was the 16th asteroid ever discovered.

Asteroid 16 Psyche has been estimated to been worth $10,000 quadrillion but the new findings could slightly devalue the iron-rich asteroid. The other well-studied asteroid, Bennu, contains a lot of carbonaceous chondrite material and has porosity of over 50%, which is a classic characteristic of a rubble pile. Such high porosity is common for relatively small and low-mass objects such as Bennu -- which is only as large as the Empire State Building -- because a weak gravitational field prevents the object's rocks and boulders from being packed together too tightly. But for an object the size of 16 Psyche to be so porous is unexpected. Past estimates of 16 Psyche's composition were done by analyzing the sunlight reflected off its surface. The pattern of light matched that of other metallic objects. The researchers also believe the carbonaceous material on 16 Psyche's surface is rich in water, so they will next work to merge data from ground-based telescopes and spacecraft missions to other asteroids to help determine the amount of water present.

VENUS' TECTONICS REVEAL GEOLOGICAL SECRETS :
North Carolina State University

A new analysis of Venus' surface shows evidence of tectonic motion in the form of crustal blocks that have jostled against each other like broken chunks of pack ice. The movement of these blocks could indicate that Venus is still geologically active and give scientists insight into both exoplanet tectonics and the earliest tectonic activity on Earth. The finding is important because Venus has long been assumed to have an immobile solid outer shell, or lithosphere, just like Mars or Earth's moon. In contrast, Earth's lithosphere is broken into tectonic plates, which slide against, apart from, and underneath each other on top of a hot, weaker mantle layer. An international group of researchers used radar images from NASA's Magellan mission to map the surface of Venus. In examining the extensive Venusian lowlands that make up most of the planet surface, they saw areas where large blocks of the lithosphere seem to have moved: pulling apart, pushing together, rotating and sliding past each other like broken pack ice over a frozen lake. The team created a computer model of this deformation, and found that sluggish motion of the planet's interior can account for the style of tectonics seen at the surface. These observations tell us that interior motion is driving surface deformation on Venus, in a similar way to what happens on Earth. Plate tectonics on Earth are driven by convection in the mantle. The mantle is hot or cold in different places, it moves, and some of that motion transfers to Earth's surface in the form of plate movement. A variation on that theme seems to be playing out on Venus as well. It's not plate tectonics like on Earth -- there aren't huge mountain ranges being created here, or giant subduction systems -- but it is evidence of deformation due to interior mantle flow, which hasn't been demonstrated on a global scale before.

The deformation associated with these crustal blocks could also indicate that Venus is still geologically active. We know that much of Venus has been volcanically resurfaced over time, so some parts of the planet might be really young, geologically speaking. But several of the jostling blocks have formed in and deformed these young lava plains, which means that the lithosphere fragmented after those plains were laid down. This gives us reason to think that some of these blocks may have moved geologically very recently -- perhaps even up to today. The researchers are optimistic that Venus' newly recognized "pack ice" pattern could offer clues to understanding tectonic deformation on planets outside of our solar system, as well as on a much younger Earth. The thickness of a planet's lithosphere depends mainly upon how hot it is, both in the interior and on the surface. Heat flow from the young Earth's interior was up to three times greater than it is now, so its lithosphere may have been similar to what we see on Venus today: not thick enough to form plates that subduct, but thick enough to have fragmented into blocks that pushed, pulled, and jostled.

BETELGEUSE'S BRIGHTNESS DIP SOLVED
ESO

When Betelgeuse, a bright orange star in the constellation of Orion, became visibly darker in late 2019 and early 2020, the astronomy community was puzzled. A team of astronomers have now published new images of the star's surface, taken using the European Southern Observatory's Very Large Telescope (ESO's VLT), that clearly show how its brightness changed. The new research reveals that the star was partially concealed by a cloud of dust, a discovery that solves the mystery of the "Great Dimming" of Betelgeuse. Betelgeuse's dip in brightness -- a change noticeable even to the naked eye -- led astronomers to point ESO's VLT towards the star in late 2019. An image from December 2019, when compared to an earlier image taken in January of the same year, showed that the stellar surface was significantly darker, especially in the southern region. But the astronomers weren't sure why. The team continued observing the star during its Great Dimming, capturing two other never-before-seen images in January 2020 and March 2020. By April 2020, the star had returned to its normal brightness. In their new study, the team revealed that the mysterious dimming was caused by a dusty veil shading the star, which in turn was the result of a drop in temperature on Betelgeuse's stellar surface. Betelgeuse's surface regularly changes as giant bubbles of gas move, shrink and swell within the star. The team concludes that some time before the Great Dimming, the star ejected a large gas bubble that moved away from it. When a patch of the surface cooled down shortly after, that temperature decrease was enough for the gas to condense into solid dust. Rather than just the result of a dusty outburst, there was some speculation online that Betelgeuse's drop in brightness could signal its imminent death in a spectacular supernova explosion. A supernova hasn't been observed in our galaxy since the 17th century, so present-day astronomers aren't entirely sure what to expect from a star in the lead-up to such an event. However, this new research confirms that Betelgeuse's Great Dimming was not an early sign that the star was heading towards its dramatic fate.

DARK MATTER SLOWING SPIN OF MILKY WAY'S GALACTIC BAR
University College London

The spin of the Milky Way's galactic bar, which is made up of billions of clustered stars, has slowed by about a quarter since its formation, according to a new study. For 30 years, astrophysicists have predicted such a slowdown, but this is the first time it has been measured. The researchers say it gives a new type of insight into the nature of dark matter, which acts like a counterweight slowing the spin. In the study, researchers analysed Gaia space telescope observations of a large group of stars, the Hercules stream, which are in resonance with the bar -- that is, they revolve around the galaxy at the same rate as the bar's spin. These stars are gravitationally trapped by the spinning bar. The same phenomenon occurs with Jupiter's Trojan and Greek asteroids, which orbit Jupiter's Lagrange points (ahead and behind Jupiter). If the bar's spin slows down, these stars would be expected to move further out in the galaxy, keeping their orbital period matched to that of the bar's spin. The researchers found that the stars in the stream carry a chemical fingerprint -- they are richer in heavier elements (called metals in astronomy), proving that they have travelled away from the galactic centre, where stars and star-forming gas are about 10 times as rich in metals compared to the outer galaxy. Using this data, the team inferred that the bar -- made up of billions of stars and trillions of solar masses -- had slowed down its spin by at least 24% since it first formed.

The Milky Way, like other galaxies, is thought to be embedded in a 'halo' of dark matter that extends well beyond its visible edge. Dark matter is invisible and its nature is unknown, but its existence is inferred from galaxies behaving as if they were shrouded in significantly more mass than we can see. There is thought to be about five times as much dark matter in the Universe as ordinary, visible matter. Alternative gravity theories such as modified Newtonian dynamics reject the idea of dark matter, instead seeking to explain discrepancies by tweaking Einstein's theory of general relativity. The Milky Way is a barred spiral galaxy, with a thick bar of stars in the middle and spiral arms extending through the disc outside the bar. The bar rotates in the same direction as the galaxy.

GIANT 'BLINKING' STAR TOWARDS CENTRE OF MILKY WAY
University of Cambridge

An international team of astronomers observed the star, VVV-WIT-08, decreasing in brightness by a factor of 30, so that it nearly disappeared from the sky. While many stars change in brightness because they pulsate or are eclipsed by another star in a binary system, it's exceptionally rare for a star to become fainter over a period of several months and then brighten again. The researchers believe that VVV-WIT-08 may belong to a new class of 'blinking giant' binary star system, where a giant star -- 100 times larger than the Sun -- is eclipsed once every few decades by an as-yet unseen orbital companion. The companion, which may be another star or a planet, is surrounded by an opaque disc, which covers the giant star, causing it to disappear and reappear in the sky. Since the star is located in a dense region of the Milky Way, the researchers considered whether some unknown dark object could have simply drifted in front of the giant star by chance. However, simulations showed that there would have to be an implausibly large number of dark bodies floating around the Galaxy for this scenario to be likely. One other star system of this sort has been known for a long time. The giant star Epsilon Aurigae is partly eclipsed by a huge disc of dust every 27 years, but only dims by about 50%. A second example, TYC 2505-672-1, was found a few years ago, and holds the current record for the eclipsing binary star system with the longest orbital period -- 69 years -- a record for which VVV-WIT-08 is currently a contender. The UK-based team has also found two more of these peculiar giant stars in addition to VVV-WIT-08, suggesting that these may be a new class of 'blinking giant' stars for astronomers to investigate.

VVV-WIT-08 was found by the VISTA Variables in the Via Lactea survey (VVV), a project using the British-built VISTA telescope in Chile and operated by the European Southern Observatory, that has been observing the same one billion stars for nearly a decade to search for examples with varying brightness in the infrared part of the spectrum. While VVV-WIT-08 was discovered using VVV data, the dimming of the star was also observed by the Optical Gravitational Lensing Experiment (OGLE), a long-running observation campaign run by the University of Warsaw. OGLE makes more frequent observations, but closer to the visible part of the spectrum. These frequent observations were key for modelling VVV-WIT-08, and they showed that the giant star dimmed by the same amount in both the visible and infrared light. There now appear to be around half a dozen potential known star systems of this type, containing giant stars and large opaque discs.

SURVEY OF 'NURSERIES' WHERE STARS ARE BORN
Ohio State University

Over the past five years, an international team of researchers has conducted the first systematic survey of "stellar nurseries" across our part of the Universe, charting the more than 100,000 of these nurseries across more than 90 nearby galaxies and providing new insights into the origins of stars. Every star in the sky, including our own Sun, was born in one of these stellar nurseries. These nurseries are responsible for building galaxies and making planets, and they're just an essential part in the story of how we got here. But this is really the first time we have a complete view of these stellar nurseries across the whole nearby Universe. The project is called PHANGS-ALMA, and the research was possible thanks to the ALMA telescope array high in the Andes mountains in Chile. PHANGS-ALMA can use ALMA to take pictures of many galaxies, and these pictures are as sharp and detailed as those taken by optical telescopes. The survey has expanded the amount of data on stellar nurseries by more than tenfold. That has given astronomers a much more accurate perspective of what these nurseries are like across our corner of the Universe. Based on these measurements, astronomers have found that stellar nurseries are surprisingly diverse across galaxies, live only a relatively short time in astronomical terms, and are not very efficient at making stars. The diversity of these stellar nurseries came as something of a surprise. For a long time, conventional wisdom among astronomers was that all stellar nurseries looked more or less the same. But with this survey we can see that this is really not the case. While there are some similarities, the nature and appearance of these nurseries change within and among galaxies, just like cities or trees may vary in important ways as you go from place to place across the world. For example, nurseries in larger galaxies, and those in the centre of galaxies, tend to be denser and more massive, and much more turbulent. Star formation is much more violent in these clouds, findings suggest. So the properties of these nurseries and even their ability to make stars seem to depend on the galaxies they live in.

Results from the survey also showed that these stellar nurseries live for only 10 to 30 million years, which is a relatively short time in astronomical terms. And the team used the same measurements to gauge how efficiently these stellar nurseries turned their gas and dust into stars -- and it turned out they weren't that efficient. This survey is allowing us to build a much more complete picture of the life cycle of these regions, and we're finding they are short-lived and inefficient. It's not random chance destroying these nurseries, but the new stars that they make. The radiation and heat that come out of these young stars begins to disperse and dissolve the clouds, eventually destroying them before they can convert most of their mass.

HUBBLE CONFIRMS GALAXIES LACKING DARK MATTER
Institute for Advanced Study

The most accurate distance measurement yet of ultra-diffuse galaxy (UDG) NGC1052-DF2 (DF2) confirms beyond any shadow of a doubt that it is lacking in dark matter. The newly measured distance of 22.1 +/-1.2 megaparsecs was obtained by an international team of researchers. The results are based on 40 orbits of NASA's Hubble Space Telescope, with imaging by the Advanced Camera for Surveys and a "tip of the red giant branch" (TRGB) analysis, the gold standard for such refined measurements. In 2019, the team published results measuring the distance to neighbouring UDG NGC1052-DF4 (DF4) based on 12 Hubble orbits and TRGB analysis, which provided compelling evidence of missing dark matter. This preferred method expands on the team's 2018 studies that relied on "surface brightness fluctuations" to gauge distance. Both galaxies were discovered with the Dragonfly Telephoto Array at the New Mexico Skies observatory. In addition to confirming earlier distance findings, the Hubble results indicated that the galaxies were located slightly farther away than previously thought, strengthening the case that they contain little to no dark matter. If DF2 were closer to Earth, as some astronomers claim, it would be intrinsically fainter and less massive, and the galaxy would need dark matter to account for the observed effects of the total mass. Dark matter is widely considered to be an essential ingredient of galaxies, but this study lends further evidence that its presence may not be inevitable. While dark matter has yet to be directly observed, its gravitational influence is like a glue that holds galaxies together and governs the motion of visible matter. In the case of DF2 and DF4, researchers were able to account for the motion of stars based on stellar mass alone, suggesting a lack or absence of dark matter. Ironically, the detection of galaxies deficient in dark matter will likely help to reveal its puzzling nature and provide new insights into galactic evolution.

While DF2 and DF4 are both comparable in size to the Milky Way galaxy, their total masses are only about one percent of the Milky Way's mass. These ultra-diffuse galaxies were also found to have a large population of especially luminous globular clusters. This research has generated a great deal of scholarly interest, as well as energetic debate among proponents of alternative theories to dark matter, such as Modified Newtonian dynamics (MOND). However, with the team's most recent findings -- including the relative distances of the two UDGs to NGC1052 -- such alternative theories seem less likely. Additionally, there is now little uncertainty in the team's distance measurements given the use of the TRGB method. Based on fundamental physics, this method depends on the observation of red giant stars that emit a flash after burning through their helium supply that always happens at the same brightness. Moving forward, researchers will continue to hunt for more of these oddball galaxies, while considering a number of questions such as: How are UDGs formed? What do they tell us about standard cosmological models? How common are these galaxies, and what other unique properties do they have? It will take uncovering many more dark matter-less galaxies to resolve these mysteries and the ultimate question of what dark matter really is.

'CHANGING-LOOK' BLAZAR DISCOVERED
University of Oklahoma

Astronomers have discovered a "changing-look" blazar -- a powerful active galactic nucleus powered by supermassive black hole at the centre of a galaxy. Blazars appear as parallel rays of light or particles, or jets, pointing to observers and radiating across all wavelengths of the electromagnetic spectrum. These jets span distances on the million light-year scales and are known to impact the evolution of the galaxy and galaxy cluster in which they reside via the radiation. These features make blazars ideal environments in which to study the physics of jets and their role in galaxy evolution. They are a unique kind of AGN with very powerful jets. Jets are a radio mode of feedback and because of their scales, they penetrate the galaxy into their large-scale environment. The origin of these jets and processes driving the radiation are not well-known. Thus, studying blazars allows us to understand these jets better and how they are connected to other components of the AGN, like the accretion disk. These jets can heat up and displace gas in their environment affecting, for example, the star formation in the galaxy. The team's research highlights the results of a campaign to investigate the evolution of a blazar known as B2 1420+32. At the end of 2017, this blazar exhibited a huge optical flare, a phenomenon captured by the All Sky Automated Survey for SuperNovae telescope network. The team followed this up by observing the evolution of its spectrum and light curve over the next two years and also retrieved archival data available for this object. The campaign, with data spanning over a decade, has yielded some most exciting results. There is dramatic variability in the spectrum and multiple transformations between the two blazar sub-classes for the first time for a blazar, thus giving it the name 'changing-look' blazar.

The team concluded that this behaviour is caused by the dramatic continuum flux changes, which confirm a long-proposed theory that separates blazars into two major categories. In addition, astronomers see several very large multiband flares in the optical and gamma-ray bands on different timescales and new spectral features. Such extreme variability and the spectral features demand dedicated searches for more such blazars, which will allow them to utilize the dramatic spectral changes observed to reveal AGN/jet physics, including how dust particles around supermassive black holes are destructed by the tremendous radiation from the central engine and how energy from a relativistic jet is transferred into the dust clouds, providing a new channel linking the evolution of the supermassive black hole with its host galaxy. The team is very excited by the results of discovering a changing-look blazar that transforms itself not once, but three times, between its two sub-classes, from the dramatic changes in its continuum emission. These results open the door to more such studies of highly variable blazars and their importance in understanding AGN physics.

CHIME DISCOVERS OVER 500 FAST RADIO BURSTS
Massachusetts Institute of Technology

To catch sight of a fast radio burst is to be extremely lucky in where and when you point your radio dish. Fast radio bursts, or FRBs, are oddly bright flashes of light, registering in the radio band of the electromagnetic spectrum, that blaze for a few milliseconds before vanishing without a trace. These brief and mysterious beacons have been spotted in various and distant parts of the Universe, as well as in our own galaxy. Their origins are unknown, and their appearance is unpredictable. Since the first was discovered in 2007, radio astronomers have only caught sight of around 140 bursts in their telescopes. Now, a large stationary radio telescope in British Columbia has nearly quadrupled the number of fast radio bursts discovered to date. The telescope, known as CHIME, for the Canadian Hydrogen Intensity Mapping Experiment, has detected 535 new fast radio bursts during its first year of operation, between 2018 and 2019. Scientists with the CHIME Collaboration, including researchers at MIT, have assembled the new signals in the telescope's first FRB catalogue, which they will present this week at the American Astronomical Society Meeting. The new catalogue significantly expands the current library of known FRBs, and is already yielding clues as to their properties. For instance, the newly discovered bursts appear to fall in two distinct classes: those that repeat, and those that don't. Scientists identified 18 FRB sources that burst repeatedly, while the rest appear to be one-offs. The repeaters also look different, with each burst lasting slightly longer and emitting more focused radio frequencies than bursts from single, non-repeating FRBs. These observations strongly suggest that repeaters and one-offs arise from separate mechanisms and astrophysical sources. With more observations, astronomers hope soon to pin down the extreme origins of these curiously bright signals. CHIME comprises four massive parabolic radio antennas, roughly the size and shape of snowboarding half-pipes, located at the Dominion Radio Astrophysical Observatory in British Columbia, Canada. CHIME receives radio signals each day from half of the sky as the Earth rotates. While most radio astronomy is done by swivelling a large dish to focus light from different parts of the sky, CHIME stares, motionless, at the sky, and focuses incoming signals using a correlator -- a powerful digital signalling processor that can work through huge amounts of data, at a rate of about 7 terabits per second, equivalent to a few percent of the world's internet traffic.

Over the first year of operation, CHIME detected 535 new fast radio bursts. When the scientists mapped their locations, they found the bursts were evenly distributed in space, seeming to arise from any and all parts of the sky. From the FRBs that CHIME was able to detect, the scientists calculated that fast radio bursts, bright enough to be seen by a telescope like CHIME, occur at a rate of about 9,000 per day across the entire sky -- the most precise estimate of FRBs overall rate to date. As radio waves travel across space, any interstellar gas, or plasma, along the way can distort or disperse the wave's properties and trajectory. The degree to which a radio wave is dispersed can give clues to how much gas it passed through, and possibly how much distance it has travelled from its source. For each of the 535 FRBs that CHIME detected, astronomers measured its dispersion, and found that most bursts likely originated from far-off sources within distant galaxies. The fact that the bursts were bright enough to be detected by CHIME suggests that they must have been produced by extremely energetic sources. As the telescope detects more FRBs, scientists hope to pin down exactly what kind of exotic phenomena could generate such ultrabright, ultrafast signals. Scientists also plan to use the bursts, and their dispersion estimates, to map the distribution of gas throughout the Universe. Each FRB gives us some information of how far they've propagated and how much gas they've propagated through. With large numbers of FRBs, we can hopefully figure out how gas and matter are distributed on very large scales in the universe. So, alongside the mystery of what FRBs are themselves, there's also the exciting potential for FRBs as powerful cosmological probes in the future.

PROBLEMS WITH HUBBLE SPACE TELESCOPE
Physics.org

The Hubble Space Telescope, which has been peering into the Universe for more than 30 years, has been down for the past week. The problem is a payload computer that stopped working the US space agency said. It insisted the telescope itself and scientific instruments that accompany it are "in good health." NASA said initial evidence pointed to a degrading computer memory module as the source of the computer problem. An attempt to switch to a back-up memory module also failed. The technology for the payload computer dates back to the 1980s, and it was replaced during maintenance work in 2009. Launched in 1990, the Hubble Space Telescope revolutionized the world of astronomy and changed our vision of the Universe as it sent back images of the solar system, the Milky Way and distant galaxies. NASA plans to continue its efforts to resolve the problem. 





Bulletin compiled by Clive Down

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Astronomy Group / The Night Sky in July 2021
July 04, 2021, 01:34:26 pm
The Night Sky in July 2021
Hello everyone here is the latest monthly night sky tips for July 2021. sorry it is a little late, but I was awy in Nottingham last weekend. All the bright planets make an appearance this month. While Mars is as dim as it gets, the Red Planet appears alongside Venus and the Moon in the evening sky for a photogenic apparition. Jupiter and Saturn rise after midnight in the southeast, each planet slowly brightening and growing on its way to opposition next month. They are both spectacular in a telescope right now. And little Mercury makes a good apparition in the eastern morning twilight before the sun rises. While it's mostly planets this month, don't forget about the Milky Way emerging in the darkening east-south-eastern sky. Turn your optics along this spectacular river of stars to glimpse the many clusters, nebulae, and star clouds in our part of the galaxy. Here's what's in the night sky this month...

The Night Sky in July 2021.pdf