When astronomers talk about an optical telescope, they often mention the size of its mirror. Thats because the larger your mirror, the sharper your view of the heavens can be. Its known as resolving power, and it is due to a property of light known as diffraction. When light passes through an opening, such as the opening of the telescope, it will tend to spread out or diffract. The smaller the opening, the more the light spreads making your image more blurry. This is why larger telescopes can capture a sharper image than smaller ones.

Diffraction doesnt just depend on the size of your telescope, it also depends on the wavelength of light you observe. The longer the wavelength, the more light diffracts for a given opening size. The wavelength of visible light is very small, less than a millionth of a meter in length. But radio light has a wavelength that is a thousand times longer. If you want to capture images as sharp as those of optical telescopes, you need a radio telescope that is a thousand times larger than an optical one. Fortunately, we can build radio telescopes this large thanks to a technique known as interferometry.

To build a high-resolution radio telescope, you cant simply build a huge radio dish. You would need a dish more than 10 kilometers across. Even the largest radio dish, Chinas FAST telescope, is only 500 meters across. So instead of building a single large dish, you build dozens or hundreds of smaller dishes that can work together. It is a bit like using only parts of a great big mirror instead of the whole thing. If you did this with an optical telescope your image wouldnt be as bright, but it would be almost as sharp.

But its not as simple as building lots of little antenna dishes. With a single telescope, the light from a distant object enters the telescope and is focused by the mirror or lens onto a detector. The light that left the object at the same time reaches the detector at the same time, so your image is in sync. When you have an array of radio dishes, each with their own detector, the light from your object will reach some antenna detectors sooner than others. If you just combined all your data you would have a jumbled mess. This is where interferometry comes in.

Each antenna in your array observes the same object, and as they do they each mark the time of the observation very precisely. This way you have dozens or hundreds of streams of data, each with unique timestamps. From the timestamps, you can put all the data back in sync. If you know that dish B gets a single 2 microseconds after dish A, you know signal B has to be shifted forward 2 microseconds to be in sync.

The math for this gets really complicated. In order for interferometry to work, you have to know the time difference between each pair of antenna dishes. For 5 dishes thats 15 pairs. But the VLA has 26 active dishes or 325 pairs. ALMA has 66 dishes, which makes for 2,145 pairs. Not only that, as the Earth rotates the direction of your object shifts relative to the antenna dishes, which means the time between the signals changes as you make observations. You have to keep track of all of it in order to correlate the signals. This is done with a specialized supercomputer known as a correlator. It is specifically designed to do this one computation. It is the correlator that lets dozens of antenna dishes act as a single telescope.

It has taken decades to refine and improve radio interferometry, but it has become a common tool for radio astronomy. From the inauguration of the VLA in 1980 to the first light of ALMA in 2013, interferometry has given us extraordinarily high-resolution images. The technique is now so powerful that it can be used to connect telescopes all over the world.

In 2009 radio observatories across the world agreed to work together on an ambitious project. They used interferometry to combine their telescopes to create a virtual telescope as large as a planet. It is known as the Event Horizon Telescope, and in 2019 it gave us our first image of a black hole.

With teamwork and interferometry, we can now study one of the most mysterious and extreme objects in the universe.

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How Interferometry Works, and Why it's so Powerful for Astronomy - Universe Today

Dark matter dogma

Pavel Kroupa, an astrophysicist at the University of Bonn in Germany, is among these standard model critics. According to him, dark matter has become dogma. He cites a handful of real-world properties seen in galaxies that dont make sense with dark matter. And he also questions many fundamental and widely-accepted aspects of modern cosmology, from the idea that galaxies can merge to whether the Cosmic Microwave Background is really evidence of the Big Bang.

Kroupa has spent the past two decades pushing MOND, an alternative theory of the universe. Scientists who support this model believe that the most puzzling aspects of the cosmos the ones that led astronomers to discover dark matter and dark energy can actually be explained with slight modifications to Newtons laws describing gravity.

But to convince the larger scientific community, contrarians like Kroupa have to show that MOND can actually recreate our universe while also explaining the same mysteries that first led astronomers to embrace the dark side. And until now, computer simulations using MOND have failed to build virtual galaxies that look like the real ones we see today.

So, other scientists skeptical of the standard model see this new study as a potential milestone.

This is clearly an important study, because MOND was often criticized for not being able to describe galaxy formation in the same successful way as models based on dark matter, says University of Amsterdam theoretical physicist Erik Verlinde, a prominent dark matter critic who was not involved in the research.

Excerpt from:

Controversial simulation creates galaxies without using dark matter - Astronomy Magazine

Photo: Heather Couper.

Heather Couper, one of the UKs most prolific astronomy broadcasters and writers, who inspired many to take up stargazing, has died at the age of 70.

Couper came to prominence in the 1980s, writing and presenting two landmark Channel 4 television series, The Planets (1985) and The Stars (1988), as well as The Neptune Encounter (1989) for ITV, which was made under the auspices of her production company Pioneer Productions, which she founded with her long-time friend and collaborator Nigel Henbest and director Stuart Carter. She also narrated Pioneer Productions award-winning Channel 4 documentary Electric Skies (1994), about lightning, as well as the ten-part Raging Planet series (1997) and Space Shuttle: Human Time Bomb? (2003). Couper has also presented numerous radio documentaries, including Radio Fours Cosmic Quest about the history of astronomy, and the long-running Seeing Stars on the BBC World Service, presented alongside Nigel Henbest.

She graduated from the University of Leicester with a BSc in Astronomy and Physics, although by her own admission in an interview for The Independent (for whom she was also a columnist), she was not a model student at school or university. However, it was her passion for astronomy, having witnessed a green meteor as a child, that spurred her on. After leaving research half way through her PhD studies at The University of Oxford, she joined the planetarium at the Royal Observatory, Greenwich as Senior Lecturer, where she remained until 1983 when she departed to pursue her media career.

Couper helped break down boundaries for women in astronomy. The year after leaving Greenwich she was elected President of the British Astronomical Association the first woman, and the second youngest person (at the age of 35), to hold the position. Between 1987 and 1989 she held the position of President for what is now known as The Society for Popular Astronomy. She was one of the speakers at the very first European AstroFest conference in 1992.

In 1993, she became Professor of Astronomy at Gresham College in London the first female professor at Gresham in its 400-year history (Carolin Crawford and Katherine Blundell have since followed in her footsteps), where she gave public talks on astronomy for three years. And of course, as one of the public faces of astronomy on television, she inspired many girls, as well as boys (including a certain Editor of Astronomy Now magazine), to take an interest in astronomy.

She was also a prolific writer alongside Nigel Henbest, with dozens of titles spanning forty years, including companions to her TV series The Planets and The Stars, The Secret Life of Space, and her most recent books including Philips 2020 Stargazing Month by Month and The Universe Explained: A Cosmic Q&A, published by Firefly.

In 1994 Couper was elected to serve on the Millennium Commission, which dished out money raised by the National Lottery to good causes. She remained on the commission until it closed in 2009, and in 2007 she was awarded a CBE by the Queen for her work on both the commission and her life-long mission to promote astronomy.

Couper also has an asteroid named after her, asteroid 3922 Heather.

She died in her sleep at Stoke Mandeville Hospital in Buckinghamshire, on 19 February 2020, following a short illness.

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Heather Couper, 19492020 - Astronomy Now Online

A University of Arizona astronomer has his eye on a mysteriously dimming star in outer space.

Narsi Anugu is a postdoctoral scholar at the UA studying interstellar space. He is focusing on the star Betelgeuse, 642.5 light years from earth. The star's light has been dimming for the past several months, and some scientists speculate it is on the verge of exploding, or going supernova. Anugu thinks if that happens, the resulting phenomenon will create a boon for space science.

This will boost astronomy, clear up many questions about whether astronomy is interesting, and increase funding," he said. "Every astronomer would love to see that.

Betelgeuse is seen from Earth as part of the popular constellation Orion, the hunter. The star marks the shoulder of the hunter on the left side of the figure to a viewer from Earth. Scientists say whenever Betelgeuse explodes, it will be visible in Earth's daylight sky and would be bright enough to cast shadows at night. But they cautiously add the event might not happen for another 100,000 years.

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Star Betelgeuse's mysterious dimming has the attention of UA astronomer - Arizona Public Media

Heather Couper, who has died aged 70, was just seven when she spotted what looked like a bright-green meteor in the sky. Her airline pilot father told her there was no such thing, but newspapers subsequently reported on a shooting star and she set her heart on becoming an astronomer.

At the age of 16, she wrote to Patrick Moore, whose television programme The Sky at Night inspired viewers to look to the heavens, and askedwhether being female might hamper her ambitions. Being a girl is no problem at all, Moore replied.

So she carved out a career as an astronomer and, from 1978 to 1984, while lecturing on the subject, was often seen as a guest or co-presenter on The Sky at Night.

Sharing the full story, not just the headlines

She also succeeded Moore as president of the British Astronomical Association (1984-86), the first woman in the role one previously occupied by worthy old gentlemen who preferred to remain discreetly out of the public eye, aside from Moore, according to New Scientist magazine at the time.

With the ability to popularise astronomy for a wide audience, Couper went freelance to become a television presenter and producer.

She and fellow astronomer Terence Murtagh hosted the 1981 childrens series Heavens Above. The wonders of the universe was the pairs theme as they examined the planets in the solar system.

Film shot by the American Viking and Voyager space probes vividly brought their words to life. There were also enlightening items such as an imaginary trip to Earth from a planet in the Andromeda galaxy.

Moving on to TV for grown-ups, Couper wrote and presented two of Channel 4s early science successes.

Mars, until quite recently, held out the promise of life, but now we know its a sun-bleached, sterile world, was typical of her candid assessments of the subjects in The Planets (1985).

Couper with her collaborator and lifelong companion Nigel Henbest: their Stargazing column has run in The Independent since 1987(Hencoup Enterprises/PA)

The Stars (1988) was a natural follow-up. Stars were the sparks that rescued our universe from becoming an ever-cooling and expanding vastness, explained Couper as she launched the series with the potentially worrying observation that galaxies giant, rotating star cities like our own Milky Way had been moving fatally further apart. The gravity of stars kept the universe alive, she said.

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Couper also presented the marathon30-part radio series Cosmic Quest (2008), charting the rise of science by tracing the progress of astronomy and astronomers such as Ptolemy, Copernicus and Halley through the ages.

She said her career highlight was being the astronomer aboard Concorde in 1986 showing Halleys Comet to passengers on a flight to New Zealand.

In 1999, on her 50th birthday, Asteroid 3922 Heather, discovered 28 years earlier, was named after her.

Heather Anita Couper was born in Wallasey, Cheshire, in 1949 to Anita (nee Taylor) and George Couper, and brought up in Ruislip, Middlesex.

On leaving St Marys Grammar School, Northwood (now Haydon School), she spent two years as a management trainee with Topshop, then owned by the fashion retailer Peter Robinson.

Joining a local astronomical society reignited her interest in astronomy and she began to realise her dream by working as a research assistant at Cambridge Observatories (1969-70), before graduating in astrophysics from Leicester University in 1973.

Couper became a researcher in Oxford Universitys astrophysics department and, from 1977 to 1983, a lecturer at the Greenwich Planetarium in the Royal Observatory.

Couper was author or co-author of more than 40 books (Hencoup Enterprises/PA)

She then concentrated on broadcasting. Nigel Henbest, who became her lifelong companion after they met as students at Leicester University, worked as a researcher and consultant on The Planets and The Stars, then formed Pioneer Productions in 1988 with Couper and TV director Stuart Carter to make science programmes for global markets.

For Pioneer, she presented The Neptune Encounter (1989), about Nasa spacecraft Voyager 2s flyby of the planet, and Space Shuttle Discovery (1993), as well as writing and narrating Space Shuttle: Human Time Bomb? (2003), investigating the design flaws and cost-cutting measures leading to the disintegration of the returning shuttle Columbia.

As a producer, Couper made Wonders of Weather (1996), Black Holes (1997) and Universe: Beyond the Millennium (1999), as well as episodes of Horizon and Equinox.

Her many radio series as a presenter included Starwatch (1996) and Worlds Beyond (2004-5). She was an author of more than 40 books, many with Henbest, and since 1987 the pair wrote The Independents monthly Stargazing column.

Couper was the first female professor of astronomy at Gresham College (1993-96) and, from 1994 to 2009, served as one of the millennium commissioners responsible for allocating 500m to public science projects. She was made a CBE in 2007.

Heather Couper, astronomer, born 2 June 1949, died 19 February 2020

Link:

Heather Couper: Astronomer who brought the stars to a wide audience - The Independent

For the first time, astronomers have found molecular oxygen thesame gas humans need to breathe in a galaxy outside the Milky Way.

Oxygen is the third most common element in the cosmos, after hydrogen andhelium. So astronomers once thought molecular oxygen, O2, would becommon in the space between the stars. But despite repeated searches, no onehad ever seen molecular oxygen beyond our galaxy until now.

Junzhi Wang, an astronomer at Shanghai Astronomical Observatory in China, andhis colleagues spotted the molecules calling card in a galaxy named Markarian231. Lying 560 million light-years away in the constellation Ursa Major, Markarian 231is the nearest galaxy to Earth that contains a quasar, where gaswhirls around a supermassive black hole and gets so hot that it glowsbrilliantly.(SN: 8/31/15).

Using radio telescopes in Spain and France, the astronomers saw radiation at awavelength of 2.52 millimeters, a signatureof O2s presence, the team reports in the Feb. 1 Astrophysical Journal.This is the first detection of molecular oxygen in an extragalactic object,Wang says.

Its also the most molecular oxygen ever seen outside the solarsystem. Previously, astronomers had seen the molecule in just two star-formingclouds within the Milky Way, the Orion Nebula and the Rho Ophiuchicloud(SN: 1/28/20). Astronomers think the shortage of interstellar O2 isdue to oxygen atoms and water molecules freezing onto dust grains, locking up theoxygen. In these stellar nurseries, though, shocks from bright newborn starscan rip water ice from the dust, freeing oxygen atoms to find each other andform molecules.

But even in the Orion Nebula, molecular oxygen is rare, withhydrogen molecules outnumbering oxygen molecules a million to one. Hydrogenalso dominates in Markarian 231. But molecular oxygen spans the outskirts ofthe galactic disk at abundances more than 100 times greater than in the OrionNebula.

Thats very high, says Gary Melnick, an astrophysicist at theHarvard-Smithsonian Center for Astrophysics in Cambridge, Mass., who was notinvolved in the work. There is no known explanation for an abundance of molecularoxygen that high. To confirm that the radiation really arises from O2,Melnick says the observers should look for a second wavelength from themolecule.

That wont be easy, Wang says, because other molecules also emit radiation atthose wavelengths. To shore up the case for O2, the scientists wentthrough the many molecules that give off wavelengths similar to the onedetected and found that nobody had ever seen any of those molecules in space except for O2. It is guilt by elimination, if you will, says teammember Paul Goldsmith, an astronomer at the Jet Propulsion Laboratory inPasadena, Calif.One possibleexplanation for all the O2 is that Markarian 231 goes through a morevigorous version of the Orion Nebulas oxygen-forming process. The galaxy is aprolific star factory, spawning new stars 100 times as fast as the Milky Wayand spewing out 700 solar masses of gas per year. High-speed gas from thegalaxys center may slam into gas in the disk, shaking water ice from dust grainsso that molecular oxygen can form.

In turn, that oxygen couldkeep the galaxy hyperactive: Radiation the molecule emits helps cool thegas so that some of it can collapse and create even more new stars in thegalaxy.

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Molecular oxygen has been spotted beyond the Milky Way for the first time - Science News

All those students who aim to reach for the stars, quite literally, to pursue a career inAstronomyor just want to understand the cosmos better are a part of the ongoingWinter School onAstronomybeing conducted atBM Birla Science Centrein Hyderabad from February 16 to 21. The fourth edition of the five-day camp is being attended by 60 space enthusiasts selected carefully from over 700 applicants. "We just want to offer a platform where students get to know about high-end Science and what's actually happening in the field," saysPranav Sharma, Scientific Officer and Curator of the Space Museum. What this school does is effectively combine talks with hands-on workshops which gives the participants, who are senior undergraduate and postgraduate students, a clear path that they could take towardsAstronomy. Students are participating from across India and care was taken to ensure a gender-balanced ratio; students from Tier II and III cities were given preference.

Another point to note about the school is that students from diverse backgrounds and an inclination towardsAstronomywere selected. "Interdisciplinary studies need to be encouraged and students should understand that disciplines don't have any borders," says the three-time winner of the REX Karmaveer Chakra Award. Especially with the advent of Computer Science and Big Data, everything has changed, he asserts.

What was new this year is a talk and workshop on Computational Astrophysics by none other than Prof Ashish Mahabal, anastronomerand Lead Computational and Data Scientist at the California Institute of Technology. In fact, this was what this year's session started with on February 16. On February 17 was a talk on Big Data and Deep Learning inAstronomyand Biology by Prof Ajit Kembhavi, Professor Emeritus at the Inter-University Centre forAstronomyand Astrophysics, Pune, that was also the need of the hour, as per the 27-year-old. On the last day, a talk on 'New Insights and Challenges in Probing our Nearest Star: The Sun' by Prof Siraj Hasan, former Director of the Indian Institute of Astrophysics, Bengaluru, will enthrallthe participants.

The response, needless to say, is exceptional. Many discussions, including off-stage ones, are going on wherein experts from academia and students were seen engrossed in intense talks. "This offered a great chance for the senior academicians to interact with students, something that they don't get to do on a regular basis," says the Agra-born curator.Pranav asserts that the scope ofAstronomyin India is expanding and students can make the most of it if they wish. "With projects like the CERN collaboration and the Thirty Meter Telescope that India has taken on, youngsters interested in the field have enough to look forward to," he says and concludes.

Other interesting sessions:- The Exciting World of Neutrinos by Prof Sanjib Agarwalla from Institute of Physics, Bhubaneswar- Exhibition on various sizes of kytoons (kite balloons)- The Romance ofAstronomyby Pranav Sharma, Curator of the Space Museum- Twenty Five Years of Exoplanets: What Have We Learned So Far? by Prof Manoj Puravankara, TIFR, Mumbai

Scenes from the previous schools

For more on them, visit: astrowin19.wixsite.com/astrowin20

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These 60 Hyderabad kids are falling in love with astronomy at BMBSC. Do you know how? - EdexLive

The Hubble Space Telescope has been one of the most important scientific instruments to have ever been deployed, and it has provided countless advancements to the fields of astronomy and cosmology. This fascinating video takes a look at one of the earliest and most important images the telescope took and how it continues to impact science even 25 years later.

Coming to you from Vox, this excellent video details the 1995 Hubble Space Telescope deep field observation and how it vastly changed our knowledge ofthe universe and even how astronomers work with data. The two things I have always loved about these images are the age of the light we are looking at and the sheer vastness contained in such a tiny spec (relatively speaking) of space. The image shows somegalaxies that are over 12 billion years old, meaning they were around at a relatively young time for the universe, giving us amazing insight into its history. It also boggles my mind just how much is contained in each of those little blips of light. Entire galaxies with millions orbillions of stars reside in those seemingly innocuous specs, reinforcing how the universe operates on scales of size that are truly beyond our own intuitive grasp. Check out the video above for the full story.

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How a Single Image Taken in 1995 Revolutionized Astronomy - Fstoppers

GRAND RAPIDS, Mich. (WOOD) Early Tuesday morning, a neatastronomical event will occur. Across the United States, people will be able towatch the planet Mars disappear behind the moon.

Unfortunately, its looking cloudy in West Michigan, so we wonthave the best view here. Our neighbors across the country with clearerconditions will be able to see Mars disappear behind the lit side of the moon thenreappear on the dark side around an hour later.

In Grand Rapids, Mars will disappear behind the moon around 7:12a.m., just before sunrise. It will reappear after sunrise around 8:38 a.m. Ifskies were clear, a telescope would likely still be needed to view the phenomenondue to the lighter conditions. The western United States will have a betterchance of seeing the occultation with the naked eye.

An occultation of a planet is not rare, but you have to be on theright spot of the globe to see it happen. Almost all the United States will beable to see this occultation of Mars (weather permitting) with the onlyexceptions being Hawaii, Alaska and a small portion of the PacificNorthwest.

We have a better chance of clearer conditions early Wednesdaymorning and early Thursday morning. In the pre-dawn hours on Wednesday, look tothe southeast toward the moon. You should be able to see Jupiter to the left ofthe moon.

Both Saturn and Jupiter will be close to the moon on Thursday morning. The moon will be to the lower right of Saturn and Jupiter will be to the upper right of the moon. Again, youll want to look toward the southeast at dawn.

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Look up: Astronomical event on the way - WOODTV.com

The potential launch of tens of thousands of satellitesis a serious threat to astronomy, according to the International Astronomical Union (IAU). Now, it's trying to find solutions.

The announcement came just days before SpaceX launched an additional 60 of its Starlink satellites.

Such "constellations" any collection of artificial satellites are already in wide use,powering the GPS in our cars and cellphones, for instance. But it's the massive number yet to come that has astronomers around the world deeply concerned.

"We are used to some satellites crossing the night sky, but now we're talking about thousands, some that would be bright enough to seewith the human eye," said Piero Benvenuti, an adviser at the executive committee of the IAU, which has more than 13,000 members worldwide.

In all, SpaceXplans to launch as many as 42,000 satellites, and it's not theonly one. Amazon plans to launch roughly 3,200 satellites, and OneWeb's 650 satellites. Canada also plans to launch 300 Telesat satellites.

The goal of Starlink isto bring internet connectivity to every part of the world, a goal similar to OneWeb's.

And while astronomers agree that goal is a practical one, they are concerned over not only the loss of the night sky, which is already under threat due to light pollution, but also to large-scale and very expensive observatories, like the $1 billion US, 8.4-metre, ground-based Large Synoptic Survey Telescope.

There are more and more of these all-sky surveys being put into place. Instead of looking at a small patch of sky, they scan large swaths. But moving satellites create long streaks of light in the images collected.

"Apart from their naked-eye visibility, it is estimated that the trails of the constellation satellites will be bright enough to saturate modern detectors on large telescopes," the IAU statement said. "Wide-field scientific astronomical observations will therefore be severely affected."

Reports of the visibility of a "train" of Starlink satellites began lastMay, shortly after the first batch of 60 were launched. Astronomers, both professional and amateur, posted videosand photos of the long streak of satellites dotting the night sky.

Then, in December, more satellites were launched.

But while the threat may be most felt by professionals, the IAU statement noted, "The appearance of the pristine night sky, particularly when observed from dark sites, will nevertheless be altered, because the new satellites could be significantly brighter than existing orbiting man-made objects."

As a result, the IAU, as well as other organizations like the American Astronomical Society, sought out professional astronomers to run simulations showing what would happen with tens of thousands of satellites in orbit around Earth. Thehope was to not only better understand the consequencesbut also head toward some solutions.

They found that, using an exampleof 25,000 satellites in low-Earth orbit which ranges from 160 to 2,000 kilometres above Earth and with orbits between 84 and 127 minutes at any given point, satellites above the horizon could number from 1,500 toa few thousand.

Some other notable findings:

Benvenuti is keen for more researchin order to better understand what the effects of tens of thousands of satellites could be.Right now, he said, astronomers are working with SpaceX in an effort to reduce their reflectivity called albedo and trying to work with other companies as well.

Connie Walker, an astronomer and president of the Commission B7, which is involved in the IAUconstellation analysis, saidthe idea is to find a solution suitable for everyone.

"It's going to be a long process, and I think to some extent, the various companies producing these satellite constellations are willing to try to come up with some solutions," she said. Some of the ideas being examined, she said, are changes to thecoatings of the satellites and changes to software to help observatories avoid, or compensate for, albedo.

But, she said, there is unlikely to be one quick-fix that will check off all the boxes.

The launch of satellite constellations and their consequences have largely taken the astronomical community by surprise. One of the problems is that there is no regulation surrounding the albedo of an object in orbit.

But that might change.

WATCH: Atrain of Starlink satellites crosses the sky (on theright)

The IAU plans to bring the issue to the UN Committee on the Peaceful Uses of Outer Space (COPUOS) in the coming months. They also plan to include the issue of constellations and their threat to science inthe program of the Conference on Dark and Quiet Skies for Science and Society, held by the IAU, the United Nations Office for Outer Space Affairs and the Government of Spain in October.

"We don't want to stop the progress of having this G5 interconnectivity," Benvenuti said. "But one has to consider the implications that you're creating on the environment, and in particularthe night sky."

And, he added, "We don't want to cry wolf and say it's a disaster and you can't do astronomy anymore."

But astronomy is more than just looking up at the night sky, admiring the stars or photographing them. It's about advancing knowledge and even technologies.

"The progress that we've made in the last 100 years It's absolutely astonishing how much we've learned because of astronomical observations," he said. "When you use your GPS, you apply Einstein's relativity, otherwise you wouldn't know where you are. People tend to forget about this."

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Astronomers look to preserve the night sky as thousands of satellites set to launch - CBC.ca

Two PANOSETI telescopes are installed in the recently renovated Astrograph Dome at the Lick Observatory in California. PANOSETI will use a configuration of many SETI telescopes to allow simultaneous monitoring of the entire observable sky. ( Laurie Hatch Photo via UCSD)

The search for extraterrestrial intelligence, better known as SETI, is taking advantage of a widening array of strategies ranging from sophisticated laser searches, to a new type of wide-angle optical observatory, to arrangements to conduct the search simultaneously with other scientific efforts.

But new technologies are also bringing new challenges: For example, how will radio astronomers deal with the noise created by a fast-growing number of satellites in low Earth orbit?

The technological pluses and minuses for the SETI quest, and for other strategies aimed at detecting life beyond our solar system, took the spotlight in Seattle last weekend during a session presented at the annual meeting of the American Association for the Advancement of Science.

Were bringing a Silicon Valley approach to the search for advanced life, said Andrew Siemion, whos the director of the Berkeley SETI Research Center as well as principal investigator for the 10-year, $100 million Breakthrough Listen project. Usually I add that were trying to bring the good parts of Silicon Valley to the search, not necessarily some of the bad parts.

Siemion focused on the good parts, including the public release of the second big batch of radio data from Breakthrough Listen. That campaign got its start nearly five years ago with a high-profile kickoff from Israeli-Russian tech billionaire Yuri Milner and the late British physicist Stephen Hawking.

Since then, Breakthrough Listen has forged partnerships with radio telescope arrays around the world most recently with the National Radio Astronomy Observatorys Karl G. Jansky Very Large Array, which took a star turn in the SETI movie Contact.

Were developing a system that will allow us to tap all of the data that the VLA produces and use it 24 hours a day, seven days a week to search for anomalies alongside other science, Siemion said.

If NRAO wins the go-ahead for a next-generation upgrade of the Jansky VLA, Breakthrough LIstens capability would be similarly upgraded.

This is the first radio telescope that would ever be built that would allow us to be sensitive to leakage radiation radio signals that are as weak as our isotropic emissions from the planet from a handful of nearby stars, Siemion said. In other words, it would theoretically be capable of picking up the signals coming from E.T.s smartphone on Proxima Centauri b.

Huge radio dishes arent the only instruments being used in the hunt for alien signals: Pioneer SETI astronomer Jill Tarter touted the development of a new type of wide-angle optical observatory, known as Panoramic SETI or PANOSETI, which would be capable of recording brief flashes of light. Such flashes may be associated with weird phenomena known as fast radio bursts, and theres a chance they might follow a pattern suggestive of intentional transmissions from a far-off civilization.

Two prototype PANOSETI telescopes are being tested at the Lick Observatorys Astrograph Dome in California. The plan calls for building two PANOSETI observatories, each with 80 telescopes arranged to cover the sky. If you get a pulse somewhere between a nanosecond and a second in duration, both observatories will see it, and you will be very confident of your result, Tarter explained.

Another long-running project at the SETI Institute, called LaserSETI, takes a different approach to the search for optical signals. LaserSETIs compact camera enclosures are designed to scan the entire sky for short blips of laser light, from as many as 15 sites around the world.

Since last August, the first two enclosures have been operating on the rooftop of the Robert Ferguson Observatory in Sonoma, California, Tarter said. The next two enclosures are going to be placed in Hawaii, at the Haleakala Observatory. And ultimately, well have something like this globally to look at all the sky, all the time, for transients.

Optical SETI could widen the search for alien signals to a whole new region of the electromagnetic spectrum, but theres an all-too-earthly obstacle to overcome.

Neither PANOSETI nor LaserSETI are fully funded, so we cant say when they might be complete, Tarter told the Seattle audience. If you have an opportunity to provide some funding, both of those projects would benefit from it.

As the acronym suggests, SETI looks for the characteristic patterns of intentional signals from beyond the solar system. But theres growing interest in the search for signs of less advanced life among the stars.

Were not looking for little green men, were looking for little green pond slime, said University of Washington astronomer Victoria Meadows, who heads UWs Virtual Planetary Laboratory.

In the decade ahead, NASAs James Webb Space Telescope could track down the first chemical signals of extraterrestrial life processes, perhaps through the detection of such gases as water vapor, methane and carbon dioxide in alien atmospheres. The next generation of ground-based telescopes could also contribute to the quest.

For now, the most promising nearby target for closer inspection is the TRAPPIST-1 system, which appears to have more than one potentially habitable planet. But Meadows warned that appearances can be deceiving. Computer simulations suggest that some seemingly habitable planets could have had their oceans cooked away early in the process of planetary evolution. Such planets turn out looking more like hellish Venus than habitable Earth.

If you think of the Earth as a kernel of corn, then Venus is like the popcorn of the solar system. Can we discriminate between a nice habitable planet, and one thats undergone ocean or atmospheric loss to be in the popcorn zone? Meadows said.

She said its likely to take more than the James Webb Space Telescope to nail down the chemical case for life beyond the solar system.

JWST will really give us a tantalizing glimpse that would be potentially habitable. Well get this tantalizing glimpse, but we wont get anything really definitive, Meadows said. To do that, we are going to need far more capable missions, and happily, NASA is currently considering them.

Several mission concepts with implications for astrobiology including HabEx, LUVOIR, Lynx and Origins are due to be assessed during a decadal survey of astronomical priorities.

Over the course of the next couple of decades, those new spacecraft should give astronomers a much better view of the heavens. But other types of new spacecraft are giving astronomers pause: Several companies including SpaceX, OneWeb, Telesat and Amazon are planning to put thousands of satellites in low Earth orbit to provide global broadband internet access. The satellites already launched by OneWeb and SpaceX have sparked concerns about radio interference, an issue that strikes at the heart of the traditional SETI quest.

If it happened that some civilization is transmitting in exactly one of the frequencies used by one of these companies, theres going to be a problem detecting it, NRAO Director Tony Beasley told GeekWire.

Beasley said he and other astronomers are involved in discussions with SpaceX to work out ways to minimize the potential harm, and hes hoping to have similar talks with OneWeb and the other satellite constellation companies. One of the measures being discussed would involve switching off the satellites for brief periods while they pass over sensitive radio dishes. Other measures could involve processing radio data to cancel out the satellites effects.

There are ways with our telescopes to be able to detect nearby moving objects and so we do have ways to separate them from celestial signals in some sense, Beasley said. But in general, a noisier environment just makes it harder to hear something.

If scientists do hear a confirmed signal from E.T., you can bet that the conflict over constellations would quickly fade away. So would the financial challenges that SETI astronomers currently face.

Ive been promised unlimited funding if we detect a signal, Breakthrough Listens Siemion said.

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SETI and other alien-hunting strategies are dealing with new tools and new troubles - GeekWire

When you hear the word asteroid, you probably think of something hurtling towardEarth at unfathomable speeds, ready to take us out like Thanos snapping his fingers but the asteroid Pallas has experienced violence in a whole other way.

Pallas is namedafter Pallas Athena. She was the ancient Greek goddess of wisdom, but what you might not know is that Athena was also a martial deity who was often portrayed with a helmet, shield, and spear. Pallas the asteroid looks like its been through endless cosmic battles, and all the impact craters punched into it say its really taken a beating. A strange orbit that takes it crashing through the asteroid belt is to blame. Now a research team led by Pierre Vernazza of the Laboratoire d'Astrophyisque de Marseille in France has been able to observe the asteroid like never before to reveal its violent history.

Just to give you an idea of what kind of chaos Pallas has been through, Vernazza and his team found 36 craters that exceeded 18 miles in diameter. Thats just a fifth of the diameter of the fateful Chicxulub asteroid that trashed the dinosaurs 65 million years ago.

Pallas is the largest main-belt object not yet visited by a spacecraft, making its surface geology largely unknown and limiting our understanding of its origin and collisional evolution, Vernazza and colleagues said in a study recently published in Nature Astronomy, explaining why they needed some help from computers here on Earth to start understanding it.

Pallas has a weirdly tilted orbit that has long been suspected, but finally studied using images of its pockmarked face from the Very Large Telescopes SPHERE instrument an array of four telescopessituated with 8-meter-wide mirrors that the team reserved for two years to see if they could catch Pallas orbiting as close to Earth as possible.

Vernazza and the other astronomers used the 11 images they were able to grab to generate a 3D reconstruction of what the asteroid should look like up close meaning its shape, its poles, and all its craters. The level of violence it had been through was gauged by its reputation for butting heads with everything else floating around in the asteroid belt over the past 4 billion years. Asteroids Ceres and Vesta were used as comparisons in simulations that showed every collision.

Pallas was found to have been bombarded with crashes that left behind craters on at least 10 percent of its surface, which the team said was suggestive of a violent collisional history. Something odd the team found about Pallas when compared to Ceres and Vesta was that it didnt take as much force to put a dent in Pallas. The same size of crater on either of the other two asteroids, about 25 miles in diameter, could be made by a much smaller object hitting Pallas at a high velocity. If you think about how many smaller objects are zooming through the asteroid belt compared to larger ones, you can probably imagine what Pallas goes through.

As if all that weren't enough, Pallas was also discovered to have a monster crater thought to be caused by its chemical composition, and a mysterious bright spot in its southern hemisphere whose origin remains unknown.

The Avengers dont have to put themselves at risk again to find out more but NASAmight send out satellites in the future.

(via Phys.org/Nature Astronomy)

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Watch out, Avengers: This asteroid has a more violent track record than Thanos - SYFY WIRE

In Gurtina Besla's universe, astronomy would be inclusive, diverse and accessible, and she is using a new award to make sure it is just that.

Besla, an assistant professor of astronomy at the University of Arizona, has received a five-year, $745,000 CAREER grant from the National Science Foundation for both her novel research on galaxies and dark matter and her outreach efforts to retain, mentor and support students studying STEM disciplines.

The CAREER grant is the agency's most prestigious honor in support of early-career faculty members who have the potential to serve as academic role models and lead advances in their organization's mission.

"In both her research and outreach, Besla is truly forward-thinking. The strides she is making toward enabling diversity and equity in the field of astronomy are exemplary, and I am pleased that the National Science Foundation has provided her with this richly deserved recognition," said Senior Vice President for Research and Innovation Elizabeth "Betsy" Cantwell.

With her CAREER grant, Besla plans to explore two nearby cloudlike galaxies called the Small and Large Magellanic Clouds.

"We've always thought that the smaller galaxies orbiting around the Milky Way could never actually affect our galaxy," she said.

But the Magellanic Clouds are big. Their gravitational pull, therefore, should be big, too. Not only that, but they are traveling at nearly three times the speed of sound.

"The fact that the Magellanic Clouds are this big and this fast and relatively new to our galaxy means they're messing things up. There's going to be all kinds of perturbations," Besla said. One example might be stars around our Milky Way "making weird movements" as a result of the Magellanic Clouds' presence, she added.

Besla is developing new models to simulate the impact of these galaxies and plans to publicly release them as an open-source program, small enough for undergraduate and graduate students to access on ordinary laptops. The open-source models will even come with tutorials.

It's all about access, she explained, adding, "Faculty need to think about making their data products available to students across the world."

In addition to helping further her research, the CAREER award will help Besla continue to build a program she founded in 2015 called TIMESTEP: the Tucson Initiative for Minority Engagement in Science and Technology Program.

"We want to help students graduate and get to the career paths they want and are excited about," Besla said. "We want to level the playing field so that everyone has the same information and access to opportunity."

TIMESTEP is a professional development program open to undergraduates in science, technology, engineering and math disciplines and is designed to provide them the information they need to succeed. Its 100 or so students majoring in astronomy, physics, mathematics, optical sciences, engineering and computer science meet twice a month. Half of the students in TIMESTEP are people of color.

To provide inspiration and access to mentorship, Besla invites faculty from across the country to talk to the students about their cultural heritage and how to stay true to their identity in their chosen profession.

"Of course, anyone is welcome to come to TIMESTEP, but we typically invite speakers of color and design programs for minority students. Studies show that they need it more," Besla said.

The university's designation as a Hispanic-Serving Institution "is directly relevant to the astronomy department's goal of building a diverse and inclusive community," Besla said. "The retention of Hispanic students in our program is a key part of realizing this goal. A large part of that is making sure Hispanic students have access to community."

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On Student Success, This Astronomer Walks the Walk - UANews

Picture the space around Earth filled with tens of thousands of communications satellites. That scenario is slowly coming into being, and it has astronomers concerned.

Now a group of astronomers have written a paperoutlining their detailed concerns, and how all of these satellites could have a severe, negative impact on ground-based astronomy.

SpaceX and other companies are casting their keen capitalist eyes on the space around Earth. SpaceX and OneWeb are the only companies - so far - to launch any portions of their satellite constellations.

But a number of other companies have plans to do the same, and eventually all of those satellites will number in the tens of thousands.

The astronomy community has raised some concerns about these satellite constellations. The Royal Astronomical Society and the American Astronomical Society have both released statements expressing their concern and desire to work with companies in the satellite constellation business.

Those statements are polite, cautious in their criticism, and written in the spirit of cooperation.

But this new paper lays out all of the astronomical community's concerns, backed up with data, and presses their point more insistently.

The first 240 Starlink satellites in Celestrak. (Gallozzi et al., 2020/Celestrak.)

"For centuries ground based astronomical observations have led to exceptional progresses in our scientific understanding of the Laws of Nature."

A satellite constellation is a group of artificial satellites that work together to provide global or near-global communications coverage. They have the potential to make high-speed internet available almost anywhere. Obviously, there are a lot of benefits to that.

But there are criticisms, too, and three astronomers from Italy's INAFOsservatorio Astronomico di Roma, have presented these criticisms in detail. The three are Stefano Gallozzi, Marco Scardia, and Michele Maris.

Their paper is titled "Concerns about ground based astronomical observations: A step to Safeguard the Astronomical Sky".

When you add up all the satellites that companies want to launch as part of their constellations, you get somewhere around 50,000 satellites. The question is, what effect will of those satellites have on ground-based astronomy?

The authors of the report claim that all of these satellites will inevitably damage astronomical observing.

A note to readers: English is not the first language of the authors of the paper, so some of the quotes contain small inconsistencies, but the meaning is clear.

"Depending on their altitude and surface reflectivity, their contribution to the sky brightness is not negligible for professional ground based observations," the report says in the introduction.

"With the huge amount of about 50,000 new artificial satellites for telecommunications planned to be launched in Medium and Low Earth Orbit, the mean density of artificial objects will be of >1 satellite for square sky degree; this will inevitably harm professional astronomical images."

(Gallozzi et al., 2020)

TABLE: There are only 172 stars in the whole sky exceeding the expected brightness of Starlink satellites. Higher altitude LEO satellites (e.g. over 1000 km-altitude) will be visible all the night reaching approximately the 8th magnitude.

Since SpaceX is the furthest along in deploying their constellation, their name pops up frequently in the paper. SpaceX's Starlink system has already launched almost 250 of their satellites, and they plan to deploy up to 42,000 satellites in total.

According to the paper, these satellites "will shine from the 3rd to the 7th magnitude in sky after sunset and before sun dawn."

The authors say that all of those satellites will inevitably leave trails in astronomical images, and may inhibit the search for Near Earth Objects. There's some degree of risk that we might not spot a potential impact because of all these satellites.

But it's not just images that will be negatively affected, according to the report.

"Serious concerns are common also to other wavelengths eligible for ground based investigation, in particular for radio-astronomy, whose detectors are already saturated by the ubiquitous irradiation of satellites communication from space stations as well as from the ground."

Back in May 2019, Elon Musk tried to dismiss any astronomical concerns about Starlink. Among his rather brusque dismissal of criticisms was his statement that "We need to move telelscopes (sic) to orbit anyway. Atmospheric attenuation is terrible."

Musk has a huge profile in the space community, so his words might have convinced some that there are no problems between Starlink and astronomy. But Musk is an entrepreneur, not a scientist.

For all his accomplishments, Musk is not an expert in astronomy or astronomical observing. Is his statement that Starlink "will have ~0 percent impact on advancements in astronomy," accurate and informed?

The three authors of the new paper don't seem to think so. They outline the risks that satellite constellations pose to astronomy, and it's not all about whether they're visible in optical light.

They point out that there are "dangerous effects arising from such changes in the population of small satellites. A dedicated strategy for urgent intervention to safeguard and protect each astronomical band observable from the ground is outlined."

"Without ground based observations most of current space based astronomy would be useless or impossible."

The authors start at the beginning, by pointing out the enormous advances in understanding made by ground-based observations. "For centuries ground based astronomical observations have led to exceptional progresses in our scientific understanding of the Laws of Nature." That's hard to argue with.

In the paper's first section, they talk about how space-based astronomy, or space telescopes, have contributed to knowledge. But they point out that ground-based and space-based astronomy need each other and produce the best science when they work together.

"Without ground based observations most of current space based astronomy would be useless or impossible."

It's safe to say that the authors don't agree with Musk's glib assertion that "We need to move telelscopes (sic) to orbit anyway. Atmospheric attenuation is terrible."

Maybe Musk has never heard of adaptive optics. Adaptive optics allow modern ground-based telescopes to overcome the effect of the atmosphere on observations. Upcoming telescopes like the European Extremely Large Telescope and the Thirty Meter Telescope feature adaptive optics at the heart of their designs.

The authors also point out what should be clear to anyone who thinks about it for very long: compared to ground-based astronomy, space-based telescopes are enormously expensive. And risky.

Advances in telescope technology are made here on Earth. Their deployment is the risky part, but the technologies have already been tested and developed here on Earth. As the authors of the paper point out, testing and developing new telescope technologies is not feasible in space.

"A major limitation of space based telescopes is that they can not be maintained, refurbished or repaired after launch." The Hubble is an exception, and other space telescopes have not been maintained. Once they're done, they're done.

The first Hubble servicing mission, the only space telescope to be serviced since launch. (NASA)

"Compared to ground based observatories, the average life-time of space based telescopes is of the order of a couple of decades or less. On the contrary ground based observatories lasts for several decades, with telescopes installed at the beginning of the space era again working in a profitable manner."

In short, space telescopes become technologically obsolete, while their ground-based counterparts keep on working.

We can see this with the European Southern Observatory's (ESO) Very Large Telescope (VLT). The VLT is made up of four primary units, and the first one saw first light in 1998.

Over the years its been upgraded multiple times, each time increasing its observing capabilities. Two of its instruments, SPHERE (first light June 2014) and ESPRESSO (first light September 2016), are designed to study exoplanets, something that wasn't important when the VLT was designed. Other instruments, like VISIR (VLT Imager and Spectrometer for mid-Infrared) were upgraded to study exoplanets.

Space telescopes are also costly when compared to ground-based telescopes. The James Webb Space Telescope has been in development for 20 years, and it will cost US$10 billion. But the next generation of ground-based telescopes, like the Giant Magellan Telescope and the European Extremely Large Telescope, will cost about US$1 billion each. And they will likely outlive the JWST by decades.

The nitty-gritty part of the paper deals with the actual problems that ground-based astronomy will face from satellite constellations. In some electromagnetic wavelengths, space telescopes are much more effective than ground-based telescopes. In the far Infrared for example, the atmosphere blocks much of it. But that doesn't tell the whole tale.

In the paper the authors talk about sky degradation. This degradation comes not only from light pollution on the ground, but "it is also due to artificial satellite fleets crossing and scarring observations with bright parallel streaks/trails at all latitudes."

Starlink alone would like to place up to 40,000 satellites into orbit. That's just one company out of several with plans to launch satellite constellations. Nobody knows how many there will eventually be, but it's fair to use a 50,000 satellite figure for discussion.

"Astronomers are extremely concerned by the possibility that sky seen from Earth may be blanketed by tens of thousands of satellites, which will greatly outnumber the approximately 9,000 stars that are visible to the unaided human eye," the authors say. "This is not some distant threat: it is already happening."

(NSF's National Optical-Infrared Astronomy Research Laboratory/NSF/AURA/CTIO/DELVE)

IMAGE:This is what astronomers are concerned about, Starlink satellites visible in a mosaic of an astronomical image.

The three astronomers break down all the numbers for Earth's growing fleet of satellites. Taking into account viewing angles, altitude, and brightness leads them to this conclusion:

"Thus with 50k satellites the "normality" will be a sky crowded with artificial objects: every square degree of the sky will have a satellite crawling in it along the whole observing night accessible and visible by astronomical cameras and not only by professional instrumentation."

According to the authors, all of this light pollution will be a serious detriment to astronomical observing. They acknowledge that SpaceX is experimenting with one "dark" satellite which is painted black to reduce reflectivity.

But they point out that 75 percent of the satellite's surface is solar panels, which obviously cannot be painted. They also point out problems with painting a satellite black:

"If the satellite body will be inhibited to reflect the sun light, it will absorb radiation warming too much with possible failures, thus will probably increase the risk management for the whole fleet and make the dark-coating solution ineffective or even counterproductive."

Apparent magnitude of satellites during an observing night depending on the altitude. (Gallozzi et al., 2020)

Then there's the whole problem of radio-band interference.

"Even with best coating and mitigation procedures to decrease the impact on visual astronomical observations, what it is often omitted or forgotten is that telecommunication constellations will shine in the radio wavelengths bands, observable from the ground."

There are decades old agreements from the beginning of the space age that reserve certain radio frequencies for certain uses. The frequencies of certain atoms and molecules in space are reserved for radio astronomy. These include carbon monoxide and its isotopes, and H2O.

Radio astronomers already have to contend with all kinds of interference. According to the authors, this will get much worse.

"What is not widely acknowledged is that the development of the latest generation telecommunication networks (both from space and from Earth) already has a profound impact on radio-astronomical observations (at all sub-bands): with LEO satellite fleets it is quite sure that the situation could become unbearable."

Then there's the question of legality, and which bodies can authorize the deployment of satellite constellations.

The authors draw our attention to the 1994 statement from UNESCO (United Nations Educational, Scientific and Cultural Organization).

That statement says:

"Persons belonging to future generations have the right to an uncontaminated and undamaged Earth, including pure skies; they are entitled to its enjoyment as the ground of human history of culture and social bonds that make each generation and individual a member of one human family."

The number of objects around Earth is growing rapidly. (Gallozzi et al., 2020)

That same statement from UNESCO also says "Here, World Heritage is the property of all humankind, and while there may be protective laws, enforcing this is another matter, as only States can sue other States under this type of international treaty. A State is responsible for the activities that occur within its jurisdiction whether they are authorized or unauthorized."

The three astronomers point out that since the FCC and other bodies in the United States have given approval to Starlink, they may be able to halt Starlink, too. They may even be obligated to under international law.

They also mention the Outer Space Treaty, and say "And the legal process is that the state government, this time the USA government, is legally responsible for all objects sent into outer space that launch from USA borders. That means, that it is the USA government that is responsible for the harm caused by its corporation, Starlink, sending objects into orbit that cause harm."

The paper draws to a close by pointing out possible legal actions that the international community could take to stop satellite constellations.

They could sue the FCC because in their approval they didn't take light pollution into account, which violates the National Environmental Policy Act. That act requires any federal agency to consider the environmental impact of the projects they approve. The authors claim that the FCC didn't adequately consider the light pollution from Starlink.

The international astronomy community could "sue in court for lack of jurisdiction and jurisprudence of US FCC to authorize private not geostationary satellites over other states and nations." This calls into question the FCC's right to even authorize satellite constellations that travel over other nations.

Then there's the International Court of Justice (ICJ). The three authors say the international community could sue the US government at the ICJ " to put on hold further Starlink launches to quantify the loss of public finances in damaging national and international astronomical projects."

The international astronomy community started a petition in January 2020. The community wants a hold put on Starlink and others, they want legal protections put in place for astronomical observing, and they want to limit the number of satellite constellations to a minimum.

"All of these requests come from the heartfelt concern of scientists arising from threatens to be barred from accessing the full knowledge of the Cosmos and the loss of an intangible asset of immeasurable value for humanity," the authors say.

Space is becoming more of a legal morass as time goes on. Exactly which types of activities will be allowed is unclear. Decades ago, near the beginning of the space age, laws and agreements were put in place to keep things under control.

But nobody foresaw anything like satellite constellations, and the legal framework governing space is likely going to come under a lot of pressure.

This article was originally published by Universe Today. Read the original article.

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Astronomers Have Aired Concerns About Musk's Starlink in a Paper, And It's Intense - ScienceAlert

Miguel Clarois a professional photographer, author and science communicator based in Lisbon, Portugal, who creates spectacular images of the night sky. As aEuropean Southern Observatory photo ambassador,a member ofThe World At Nightand the official astrophotographer of theDark Sky Alqueva Reserve, he specializes in astronomical "skyscapes" that connect Earth and night sky. Join Claro here as he takes us through his photograph"Orion in the Winter Sky and the Story Behind the Fainting Star Betelgeuse."

Captured during one of my private workshops on Dec. 12, 2019, this image shows a lonely stargazer enjoying the most beautiful constellation of the winter sky: Orion, the hunter.

The photo, captured from one of the landscapes of Dark Sky Alqueva Reserve in Portugal, features the bright star Betelgeuse, which is located on the hunter's left "shoulder." Many amateur and professional astronomers since last October have been reporting a decrease in brightness of the yellow-orange star, giving space for some speculation that the star is about to explode.

Related: The dimming star Betelgeuse is acting weird. Here's how to spot it in Orion's shoulder.

According to an article published by National Geographic last December, "decades of photometric data show that Betelgeuse brightens and dims in cycles, with one notable cycle vacillating on a roughly six-year time scale and another rising and falling every 425 days or so."

Scientists suspect that the red supergiant Betelgeuse has recently dimmed quite dramatically because those two periodic cycles are overlapping at minimal brightness, according to a report published in the Astronomer's Telegram by Edward Guinan, a professor of astronomy and astrophysics at Villanova University in Pennsylvania.

Astronomers have long suspected that the star might explode sometime in the next million years. It's also possible that Betelgeuse has already exploded and we just haven't seen it happen; because the star is 600 light-years away, it takes 600 years after something happens on Betelgeuse for light from that event to reach Earth. But if and when astronomers do witness the star's explosion, it will be the most astonishing astronomy event of all time.

When Betelgeuse explodes, turning into a supernova, it will briefly shine even brighter than the full moon. Then, the star will vanish forever, leaving an "empty space" in our hearts and in the mythic Orion constellation, which will still be visible in the night sky for us and many future civilizations. Without his left shoulder, however, the hunter will never look the same.

To capture this single shot, I used a Nikon D810A camera with the ISO set to 2500 and a 24-70mm lens set to 26mm at f/2.8. The exposure time was 15 seconds.

To get a print of Claro's amazing astrophotography, visit his fine-art prints store atwww.miguelclaro.com/prints. Follow us on Twitter@Spacedotcomand onFacebook.

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Orion and its dimming star Betelgeuse shine over a stargazer in this sentimental night-sky photo - Space.com

Supernova seen from Earth

With all the speculation about what a Betelgeuse supernova would look like from Earth, University of California, Santa Barbara, astronomer Andy Howell got tired of the back-of-the-envelope calculations. He put the problem to a pair of UCSB graduate students, Jared Goldberg and Evan Bauer, who created more precise simulations of the stars dying days.

The astronomers say theres still uncertainty over how the supernova would play out, but they were able to augment their accuracy using observations taken during Supernova 1987A, the closest known star to explode in centuries.

Life on Earth will be unharmed. But that doesnt mean it will go unnoticed. Goldberg and Bauer found that when Betelgeuse explodes, it will shine as bright as the half-Moon nine times fainter than the full Moon for more than three months.

All this brightness would be concentrated into one point, Howell says. So it would be this incredibly intense beacon in the sky that would cast shadows at night, and that you could see during the daytime. Everyone all over the world would be curious about it, because it would be unavoidable.

Humans would be able to see the supernova in the daytime sky for roughly a year, he says. And it would be visible at night with the naked eye for several years, as the supernova aftermath dims.

By the time it fades completely, Orion will be missing its left shoulder, adds Sarafina Nance, a University of California, Berkeley, graduate student whos published several studies of Betelgeuse.

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When Betelgeuse goes supernova, what will it look like from Earth? - Astronomy Magazine

Astronomers estimate that there is roughly one exoplanet per star in our galaxy. Of course, some stars have many planets our own Sun has eight. And some stars have none. But if a star lives long enough, forming planets seems to be the rule, rather than the exception.

That doesnt mean astronomers can map all of those billions of stars though. When it comes to exoplanets that have been measured or counted in some way, the numbers are much smaller.

The running counter of known exoplanets as of this writing stands at 4,108 confirmed worlds. But astronomers are surprisingly good at figuring out what they cant see. They know that their telescopes arent powerful or precise enough to see the stealthiest planets those that are very small, very far from their stars, or around stars very far from Earth. And conversely, there are regions of space where astronomers are pretty confident theyve found all the planets within a certain range.

By combining the knowledge of what they can see the known exoplanets with the knowledge of what they cant see the parts of space currently beyond our ability to investigate astronomers end up at the approximation of one planet per star.

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How many planets are there in the universe? - Astronomy Magazine

ReutersFeb 17, 2020 10:19:22 IST

A vaguely hourglass-shaped icy object called Arrokoth residing in the far reaches of the solar system the most distant body ever explored by a spacecraft is giving scientists intriguing clues about the formation of the planets including Earth.

Scientists on Thursday offered the fullest description yet of the composition and origin of Arrokoth based on data from NASAs New Horizons spacecraft, which whizzed past it last year.

Arrokoth, located 6.6 billion km from Earth in a region beyond the planet Neptune called the Kuiper Belt, boasts a uniformly reddish surface that is smooth and undulating with few craters. It is coated with frozen methanol a type of alcohol and unidentified complex organic molecules.

Arrokoth is a planet that is comprised of two lobes looking somewhat like giant wheels of cheese fused together by a bridge. Image credit: NASA

About 36 km long and 20 km wide, it is classified as a planetesimal, objects that were among the solar systems original building blocks. These small bodies coalesced at an early stage of the solar systems formation some 4.5 billion years ago and are a key intermediate size step on the way to building planets.

Arrokoth is comprised of two lobes looking somewhat like giant wheels of cheese fused together by a bridge.

It consists of two bodies that appear to have formed in orbit around each other from a local dust cloud, which collapsed under its own gravity within the solar nebula the huge disk of dust and gas that the solar system formed from.The two bodies then spiralled in together and merged very gently, said astronomer John Spencer of the Southwest Research Institutein Colorado, one of the researchers in the study published in the journal Science.

This suggests that planetesimals formed in localized conditions in which collision speeds were slow rather than from a gradual assembly of widely dispersed objects growing by randomly colliding with each other at higher speeds.

So we now have a clearer picture of how planets, including the Earth, were built, Spencer said.

Planetesimals previously visited by space probes were all badly battered by impactors or cooked by approaching too close to the sun. So it is thrilling to finally be able to see one still pretty much just as it was after its formation, said planetary scientist and study co-author Will Grundy of Lowell Observatory in Arizona, a New Horizons mission co-investigator.

Arrokoth is one of the thousands of small icy bodies inhabiting the Kuiper Belt, the solar systems vast third zone beyond the inner terrestrial planets and the outer gas giant planets. Its name is a Native American term for sky.

Welcome to Tech2 Innovate, Indias most definitive youth festival celebrating innovation is being held at GMR Grounds, Aerocity Phase 2, on 14th and 15th February 2020. Come and experience an amalgamation of tech, gadgets, automobiles, music, technology, and pop culture along with the whos who of the online world. Book your tickets now.

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Planetesimal Arrokoth is helping astronomers understand the formation of the planets - Firstpost

Monday, February 17Mars rises before 4 a.m. local time and climbs 20 above the southeastern horizon an hour before the Sun comes up. Glowing at magnitude 1.2 against the fainter background stars of Sagittarius the Archer, the ruddy world stands out nicely in the predawn darkness. But the real reason you should target Mars through binoculars or a telescope this morning is because of the company it keeps: The Red Planet passes between two of the Milky Ways finest star-forming regions, the Lagoon Nebula (M8) and the Trifid Nebula (M20). These two Messier objects lie just 1.4 apart and will make a marvelous backdrop for astroimagers. Unfortunately, a telescope doesnt add much to our view of Mars, revealing a bland disk that measures just 5" across.

Tuesday, February 18As spectacular as Mars passage between M8 and M20 yesterday was, this morning holds even more drama for observers in the western two-thirds of North America. Shortly before dawn, the waning crescent Moon slides in front of the Red Planet in a stunning occultation. You can view this event with your naked eye, but binoculars or a telescope reveal far more detail. Use a scope if you want to watch Mars fade away as Lunas bright limb gradually overtakes it. Depending on your location, the Moon can take up to 15 seconds to completely cover the planets featureless disk. The occultation occurs earlier the farther west you live. Although Mars has already disappeared by the time the two objects rise along the West Coast, observers there can witness the planets equally stunning reemergence from behind the Moons dark limb. Those in the mountain states get to view the disappearance against a dark sky, while Midwesterners see the same event during twilight. Unfortunately, East Coast skygazers miss out because the occultation occurs after the Sun rises. Even so, theyll enjoy a beautiful close conjunction between the two objects before dawn.

Wednesday, February 19Less than an hour after Mars rises, Jupiter pokes above the southeastern horizon. Theres no mistaking the giant planet for any other object at magnitude 1.9, it is by far the brightest point of light in the morning sky. The waning crescent Moon forms a pretty pair with Jupiter this morning, appearing just 4 to the planets right.

Thursday, February 20The Moon moves eastward an average of 13 relative to the background stars each day. That motion carries it into western Sagittarius this morning, where it lies just 2.5 to the lower right of Saturn. The two rise shortly after 5 a.m. local time and appear impressive as twilight starts to brighten the sky. The ringed planet glows at magnitude 0.6, 10 times fainter than its brilliant neighbor, Jupiter.

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Artists concept of a neutron star. The stars tiny size and extreme density give it incredibly powerful gravity at its surface. Thus this image portrays the space around the neutron star as being curved. Image via Raphael.concorde/ Daniel Molybdenum/ NASA/ Wikimedia Commons.

When at the end of its life a massive star explodes as a supernova, its core can collapse to end up as a tiny and superdense object with not much more than our suns mass. These small, incredibly dense cores of exploded stars are neutron stars. Theyre among the most bizarre objects in the universe.

A typical neutron star has about about 1.4 times our suns mass, but they range up to about two solar masses. Now consider that our sun has about 100 times Earths diameter. In a neutron star, all its large mass up to about twice as much as our suns is squeezed into a star thats only about 10 miles (15 km) across, or about the size of an earthly city.

So perhaps you can see that neutron stars are very, very dense! A tablespoon of neutron star material would weigh more than 1 billion U.S. tons (900 billion kg). Thats more than the weight of Mount Everest, Earths highest mountain.

Neutron stars are the collapsed cores of massive stars. They pack roughly the mass of our sun into a sphere with the diameter of a city. Heres a comparison of a neutron stars typical diameter with the city of Chicago. Graphic via M. Coleman Miller.

Heres how neutron stars form. Throughout much of their lives, stars maintain a delicate balancing act. Gravity tries to compress the star while the stars internal pressure exerts an outward push. The outward pressure is caused by nuclear fusion at the stars core. This fusion burning is the process by which stars shine.

In a supernova explosion, gravity suddenly and catastrophically gets the upper hand in the war it has been waging with the stars internal pressure for millions or billions of years. With its nuclear fuel exhausted and the outward pressure removed, gravity suddenly compresses the star inward. A shock wave travels to the core and rebounds, blowing the star apart. This whole process takes perhaps a couple of seconds.

But gravitys victory is not yet complete. With most of the star blown into space, the core remains, which may only possess a couple of times the mass of our sun. Gravity continues to compress it, to a point where the atoms become so compacted and so close together that electrons are violently thrust into their parent nuclei, combining with the protons to form neutrons.

Thus the neutron star gets its name from its composition. What gravity has created is a superdense, neutron-rich material called neutronium in a city-sized sphere.

What neutron stars are, and are not. If, after the supernova, the core of the star has enough mass, then according to current understanding the gravitational collapse will continue. A black hole will form instead of a neutron star. In terms of mass, the dividing line between neutron stars and black holes is the subject of much debate. Astrophysicists refer to a kind of missing mass, occurring between about two solar masses (the theoretical maximum mass of a neutron star) and five solar masses (the theoretical minimum mass of a black hole). Some expect that this mass bracket will eventually be found to be populated by ultra-lightweight black holes, but until nownone have been found.

The exact internal structure of a neutron star is also the subject of much debate. Current thinking is that the star possesses a thin crust of iron, perhaps a mile or so thick. Under that, the composition is largely neutrons, taking various forms the further down in the neutron star they are.

A neutron star does not generate any light or heat of its own after its formation. Over millions of years its latent heat will gradually cool from an intial 600,000 degrees Kelvin (1 million degrees Fahrenheit), eventually ending its life as the cold, dead remnant of a once-glorious star.

Because neutron stars are so dense, they have intense gravitational and magnetic fields. The gravity of a neutron star is about a thousand billion times stronger than that of the Earth. Thus the surface of a neutron star is exceedingly smooth; gravity does not permit anything tall to exist. Neutron stars are thought to have mountains, but they are only inches tall.

Anatomy of a pulsar. They are neutron stars that are oriented in a particular way with respect to Earth, so that we see them pulse at regular intervals. Image via Roen Kelly/ Discovermagazine.com.

Pulsars: How we know about neutron stars. Although neutron stars were long predicted in astrophysical theory, it wasnt until 1967 that the first was discovered, as a pulsar, by Dame Jocelyn Bell Burnell. Since then, hundreds more have been discovered, including the famous pulsar at the heart of the Crab Nebula, a supernova remnant seen to explode by the Chinese in 1054.

On a neutron star, intense magnetic fields focus radio waves into two beams firing into space from its magnetic poles, much like the beam of a lighthouse. If the object is oriented just so with respect to Earth so that these beams become visible from our earthly viewpoint we see flashes of radio light at regular and extremely precise intervals. Neutron stars are, in fact, the celestial timekeepers of the cosmos, their accuracy rivalling that of atomic clocks.

Neutron stars rotate extremely rapidly, and we can use the radio beams of a pulsar to measure just how fast. The fastest-rotating neutron star yet discovered rotates an incredible 716 times per second, which is about a quarter of the speed of light.

Read more about Jocelyn Bell Burnell, who discovered pulsars

Irish astronomer Jocelyn Bell Burnell was 24 years old when she noticed the odd radio pulses from space that she and her colleagues at first affectionately labeled LGMs, for little green men. Later, they understood that the pulses came from neutron stars. Fast-spinning neutron stars seen by earthly astronomers to emit radio pulses are now called radio pulsars. Image via Wikimedia Commons.

More manifestations of neutron stars in our galaxy. There are estimated to be more than a hundred million neutron stars in our Milky Way galaxy. However, many will be old and cold, and therefore difficult to detect. The unimaginably violent neutron star collisions, one of which was detected in 2017 by the LIGO gravitational wave observatories and designated GW170817, are thought to be where heavy elements like gold and platinum are created, as normal supernovae are not thought to generate the requisite pressures and temperatures.

A neutron star that has an abnormally strong magnetic field is known as a magnetar, able to pull the keys out of your pocket from as far away as the moon. The origin of magnetars is not well understood.

Neutron stars, including magnetars and pulsars, are thought to be responsible for several little-understood phenomena, including the mysterious Fast Radio Bursts (FRBs) and the so-called Soft Gamma Repeaters (SGRs).

Read more about neutron stars:

M. Coleman Miller, a professor of astronomy at University of Maryland, has a great page on neutron stars.

Five extreme facts about neutron stars, from SymmetryMagazine.org

Getting to know pulsars, the lighthouses of the cosmos, from DiscoverMagazine.com

How high are pulsar mountains? from LIGO

Sci fi alert! Dragons Egg by Robert L. Forward (out-of-print) depicts the imaginary inhabitants of the surface of a neutron star. Claudia commented: They were tiny and dense (of course) and lived at a tremendous speed. Its been a while, but I remember it as a good read. Andy added: Yes, I remember that book! Very entertaining. Its incredible to think that if the surface of a neutron star slips by as little as a millimeter, it causes a starquake.

Bottom line: Neutron stars are the collapsed cores of formerly massive stars that have been crushed to an extreme density by supernova explosions. A neutron star isnt as dense as a black hole, but its denser than any other known type of star.

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What is a neutron star? | Astronomy Essentials - EarthSky