Category Archives: Astronomy

What is Astronomy Day?

Doug Berger, while president of the Astronomical Association of Northern California at the time, started Astronomy Day in 1973 with the goal of bringing attention to the night sky. Astronomy Day happens every spring and fall on a Saturday close to the first-quarter Moon. This month, the Moon reaches first quarter on Wednesday, October 13th (October 12th for U.S. time zones).

Whether you have a telescope, binoculars, or prefer to observe with only your unaided eye, this is a great chance to head out and see some amazing things in the night sky this weekend.

Star parties, where people bring their equipment and observe together, are a great way to spend the night. These events are an inspiring experience for anyone, including beginners who are just starting to learn about astronomy.

Unfortunately, COVID-19 is still making things difficult, and many of us cant get to events easily. Instead, how about having a virtual star party? Talk to some friends or with a local astronomy club, chat online, and enjoy all things astronomical this weekend.

Here are a few things to get you started, especially if youre new to the hobby.

It is Astronomy Day isnt it? Why should everything happen at night? So, a few times during the day, note where the Sun is. That path the Sun travels across the sky is called the ecliptic, which will come in handy later.

IMPORTANT: Please, no telescopes or binoculars for this. You could severely damage your eyes. Do not stare at the Sun, lenses or not.

In the dimming autumn evening, lets look for our nearest celestial neighbor: the Moon. On Saturday after sunset, in deepening twilight, we'll see a young, waxing crescent Moon, about halfway between new and first quarter, just above the stunning gleam of the planet Venus. As the pair glide toward the horizon, lets see if we can spot earthshine, the sunlight that bounced off Earth, off the Moon, and back to our eyes. Earthshine appears a dim glow on the Moons unlit side, and its easiest to see during the Moons crescent phases. Maybe we can also catch some of the Moons features hiding in the shadows there. The pair will set about two hours after sunset, so linger here for awhile; itll be worth it.

Remember when we were watching the Suns movement across the sky and used it to imagine the ecliptic? After catching up with the Moon and Venus, follow that same imaginary line back toward the east across the southern sky. The next bright object well come to is the planet Saturn.

I wont lie, Saturns a little tough. Its not as bright as we might expect it to be; after all, its light has traveled almost 2 billion miles to get to our eyes! Still, I always love how understated and subtle it is with the naked eye. Binoculars likely wont let you see the rings, but their presence makes the planet appear a bit stretched out and egg-shaped. With a telescope, those rings come into clearer view. With optical aid, you might even be able to see its giant moon, Titan, appearing as a nearby star. (You can double-check using our interactive online tool.)

A bit farther to the east, well find unmistakable Jupiter. Its the third-brightest object in the night sky (after the Moon and Venus), and its been positively gorgeous recently. With our binoculars, we can spot its four planet-size Galilean moons: Io, Europa, Ganymede, and Callisto. Those tiny dots are each very roughly the size of Mercury.

As the night goes on, well see the Pleiades open star cluster (Messier 45) rise. The Pleiades, which looks like a tiny dipper, but isnt the famous Little Dipper, is 444 light-years from us. This makes it one of the closest open star clusters to Earth. With good vision and sufficiently dark skies, we might be able to see six or seven stars with the naked eye. Through binoculars, though, its positively jaw-dropping, with countless stars spilled across the sky. We usually think of this cluster as a wintertime object, but here it is in early October: a sneak preview of good things to come.

This ones a bit of a challenge for beginners. The Andromeda Galaxy (Messier 31) is the nearest large spiral galaxy, and in October, its well-placed for easy spotting in mid-evening. While its possible to see M31 under very dark and clear skies, most of us need binoculars or a telescope to find it.

There are two easy ways to get to it. First, face northeast and find the constellation Cassiopeia. This month, its stars sit like the number 3 in the northeast sky. Then scan the sky about 15 degrees toward the right or upper right. (Extend your fist and stick out your index and pinkie fingers in a hang loose sign, and itll be that far toward the right of Cassiopeia if youre in the Northern Hemisphere ).

Or you can star-hop with a telescope or binoculars. Start by finding Mirach, which is the second in the line of three stars extending northeast from northeastern corner of the Great Square of Pegasus. From Mirach, hop toward the northwest to Mu Andromedae, then to Nu Andromedae (see diagram below), and start scanning the sky nearby.

Either way, youll know when you see it because the galaxy almost looks like a giant thumbprint on the sky. This is a great skill to pick up because once we find it, well know exactly where to look next time, and then we can tell everyone where they can see 2.5 million-year-old light, too.

These are just a few things we can see this weekend. What else should we look for? I hope youll head out and have a great Astronomy Day, everyone! Leave a comment and let me know how it goes!

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Celebrate Fall Astronomy Day This Weekend - Sky & Telescope - SkyandTelescope.com

Astronomy day offers closer look at the sun

La Crosse, Wis. - (WXOW) - The La Crosse area Astronomy Society set up shop at Riverside Park Saturday afternoon, offering a free and up close look at the sun.

As part of an outreach effort on astronomy day, various telescopes and filters were on hand all aimed up at the sun. Anyone wanting to see the giant star or various sunspots got their chance.

The group also planned to offer some night viewing depending on cloud conditions.

"You could see the craters on the moon, the mountains and features," said Gordon Steward, society member. "When we look at Saturn you'll see the rings, if you see Jupiter you'll see the four moons."

The La Crosse area Astronomy Society has been around since 1978.

They currently set up outreach days twice a year for Astronomy day.

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Astronomy day offers closer look at the sun - WXOW.com

Over the last month, both visual and photographic amateur astronomy has been difficult. In the daytime, you might have noticed that even on the clearest of days, the sky was often not the blue one would expect but blue mixed with brown. Smoke! The fires in California and Oregon have generated so much smoke that even here in Arkansas, seeing objects in the night sky as well as trying to photograph them has been very difficult.

But -- there is always the Moon. As I write this near the end of September, it is a clear night and the night of the Full Moon for this month. It is easy to observe even in pretty bad weather and it can be very dramatic in even a small telescope.

An ongoing debate among astronomers is the question of why the Moon is so large relative to the Earth. If you look at the sizes of other moons in the Solar System and you compare these sizes to their primaries, such as Jupiter, Saturn, Uranus and Neptune, you can easily notice that the moons of these planets are tiny as compared to the sizes of the planets around which they revolve. One prominent theory has it that far in the Earth's past, the Earth was struck a glancing blow by an object about the size of the present-day Mars. The left-over debris from this collision is thought to have coalesced into our Moon. Interesting ... .

Scientists believe there have been two very different eras in the Moon's geology. In one era, the Moon was very heavily cratered. The Moon probably acted as a sort of shield, keeping the early Earth from getting as pocked with craters as the Moon has been. The Earth has had a share of meteor craters but the combination of weathering, water flow and tectonic activity have buried many craters on Earth that we might see today.

In another era of the Moon's history, there was great volcanism and lava outflow. On a night of the full Moon, one can see, with just the naked eye, places where the Moon appears quite white and other, darker areas, where the Moon is dark grey. If one were to look at the Moon in even a small telescope, one would see that some of these darker areas are dark indeed -- in some places almost black. These dark areas were thought by the Romans to be seas, but they are relatively smooth areas of lava flow or lava beds. Some of them have been cratered by meteors that fell after the great period of volcanism and lava flow, but these dark areas are usually much smoother than the cratered areas.

I have selected a photo I made that I hope shows both kinds of lunar terrain. One part of the photo shows a place on the Moon where there is much cratering and, in the bottom right part of the picture, the dark lava, mostly made of basalt, has long ago cooled into a relatively smooth plain. The very large crater in the photo is Clavius, one of the biggest craters, being some 144 miles across. If one looks at it in a telescope, one can see crater upon crater -- a history of massive bombardment, gouged into the Moon's surface.

Jupiter and Saturn are still well up in the southern sky at night. Looking south about 9 p.m. or after, Jupiter will be the brightest object there, unless the Moon is shining. Saturn will be much dimmer but quite visible, 'in front of' Jupiter as the Earth rotates and night goes forward.

In October, we can have some of the clearest and most transparent of skies for all year. This is, of course, barring rain, clouds, snow or smoke! Sometimes we even have so much dust in the air that it isn't worth trying to observe ... .

Nonetheless -- get out there and observe. As my Dad often said, "You can't catch fish if you don't have a line in the water ... ." See what you can catch!

-- Dr. David Cater is a former faculty member of JBU. Email him at [emailprotected] The opinions expressed are those of the author.

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ASTRONOMY: There's always the Moon... - Northwest Arkansas Democrat-Gazette

This composite image of GW Orionis comes from the European Southern Observatory's Very Large Telescope in Chile.

The GW Orionis star system, relatively nearby at a distance of just 1,300 light-years, couldn't be much more different from our solar system. GW Ori, as astronomers call it, is a triple-star system partly shrouded by dusty rings of space detritus where planets may be in the process of forming.

But new analysis of the protoplanetary cloud suggests that process may have already yielded some pretty big cosmic fruit.

Unlock the biggest mysteries of our planet and beyond with the CNET Science newsletter. Delivered Mondays.

Researchers led by Jeremy Smallwood, a recent Ph.D. graduate in astronomy from the University of Nevada, Las Vegas, noticed a significant and befuddling gap in the dusty discs, which are not only broken up but also warped.

"We suggest that the presence of a massive planet (or planets) in the disc separates the inner and outer discs," Smallwood and colleagues write in a paper published last month in Monthly Notices of the Royal Astronomical Society. "The disc breaking in GW Ori is likely caused by undetected planets the first planet(s) in a circumtriple orbit."

The planets hidden within the dirty belts are likely to be gas giants like Jupiter, which tend to form earlier in the history of a system than rocky planets like Earth.

Astronomers have previously discovered planets in triple-star systems, like LTT 1445Ab that has three suns in its skies, but which only orbits one of the stars. If there are confirmed planets around GW Ori, they would be the first to be seen moving around a trio of stars.

It also means there could be a lot going on in the gravitationally bound celestial dustbins whipping around distant stars.

"It's really exciting because it makes the theory of planet formation really robust," Smallwood said in a statement. "It could mean that planet formation is much more active than we thought, which is pretty cool."

And we used to think the double sunsets on the Skywalker homestead on Tatooine were mind-blowing. Truth is always stranger than fiction.

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Astronomers may have spotted first planet orbiting three stars - CNET

In a recent study,a group of international astronomers used the Atacama Large Millimeter or Submillimeter Array (ALMA) as well as the Hubble Space Telescope to investigate a cluster of six primitive galaxies. The findings of the study were just released in the journal 'Nature.'With little or no forming of stars, these sixearly galaxies were known to be "quenched." As per the study, within the first few billion years following the Big Bang, these galaxies were developed.

Previously, astronomers assumed that maybe something had interfered to prevent the formation of stars in those rich galaxies, despite the fact that they contained vast amounts of cold hydrogen gas, which is considered to be the most vital fuel in a star formation.

The study's principal author and an associate professor of astronomy at the University of Massachusetts, Amherst,Kate Whitaker statedthat,throughout history, the most gigantic galaxies in the cosmos have lived fast and furious, forming their stars in a very short period of time. During these initial stages of the universe, a gas that is the fuel for star formation, ought to be abundant.

Kate went on to explain why these 6 galaxies have no stars by stating that previouslythe astronauts used to think that these quenched galaxies slowed down a few billion years after the Big Bang. But, in the recent study, they discovered that these primitive galaxies were not actually on brakes or slowformation of stars, but instead were running on empty as they did not possess any cold gas.

The researchers discovered that galaxies' ability to convert cold gas into stars did not suddenly decline, contrary to assumptions. The stars, on the other hand, lacked frigid gas.Normally, these galaxies are so far away that identifying and resolving them is difficult, thus, the researchers employed a technique by magnifying the pictures of the galaxies which they obtained from gravitational lensing aroundneighbouringgalaxies.

Furthermore,The Hubble Space Telescope is a space telescope that was deployed onto low-Earth orbit in the year 1990 and is still operational today. Though, it was not the initial telescope, yet, it is regarded to be one of the biggest and most flexible, crucial scientific instruments as well as an astronomical public relations benefit. The Hubble telescope is one of NASA's Great Observatories and is dedicated to astronomer Edwin Hubble.

Meanwhile, the Array ALMAis a 66-radio-telescope astronomical observatory in northern Chile's the Atacama Desert that observes electromagnetic waves atmillimetreand submillimeter wavelengths. ALMA is intended to give information on early Stelliferous star creation as well as comprehensive imaging of planetary systems and planet formation.

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Astronomers unearth mystery behind 'no star formation' in six primitive galaxies - Republic World

Researchers have developed a new method to detect rogue planets outside the solar system, worlds that wander their galaxies alone without a parent star.

The technique, devised by NASA Goddard Space Flight Center scientist, Richard K. Barry, unites astronomy's futurein the form of the soon-to-launch Nancy Grace Roman Space Telescopewith its past, a method used by 19th-century astronomers to measure distances.

The Contemporaneous LEnsing Parallax and Autonomous TRansient Assay (CLEoPATRA) mission will use parallax to measure distances, but the method will be bolstered by artificial intelligence (AI) developed by Dr. Greg Olmschenk.

Olmschenk's program, RApid Machine learnEd Triage (RAMjET), will learn patterns through provided examples filtering out useless information and ensuring that of the millions of stars observed by CLEoPATRA per hour, only useful information is transmitted back to Earth.

Recent research published in The Astronomical Journal suggests that exoplanets that exist in the Universe without a parent star could be more common than stars themselves, but until now spotting them has been difficult.

"The difficulty with detecting rogue planets is that they emit essentially no light. Since detecting light from an object is the main tool astronomers use to find objects, rogue planets have been elusive," the author of that paper and Thomas Jefferson professor for Discovery and Space Exploration at Ohio State University, Scott Gaudi, told Newsweek.

The most powerful method of spotting exoplanetsplanets outside the solar systemis through the dips in light they cause as they pass in front of their parent stars. This transit method has resulted in the discovery of thousands of worlds added to the exoplanet catalog, but it doesn't work for planets that don't have host stars.

One way to spot rogue exoplanets is to wait until they cross between a distant Milky Way star and our telescopes here on Earth intercepting the light from that star. When this happens, a phenomenon called gravitational lensing, the bending of light caused by a massive object, actually causes the light from that star to brighten.

CLEoPATRA will exploit this brightening, which is called microlensing when it involves a lensing object of small mass like a planet, and use parallax to measure the distance to these rogue worlds.

"Roman [Space Telescope] will use a technique called gravitational microlensing to find rogue planets, which relies only on the gravity and thus the mass of the planet, and doesn't require detecting any light from the planet," Gaudi said

As microlensing events are both unpredictable and exceedingly rare, a telescope must monitor hundreds of millions of stars nearly continuously to spot them. And that takes a wide-field space telescope like Nancy Grace Roman Space Telescope.

Parallax is the apparent shift in the position of an object when it is observed from different positions. The most familiar example of this is holding a finger close to our face and looking at it with one eye, and then switching to the other. The finger will look like it has moved.

Astronomers in the 19th century used this phenomenon to measure the distances to close stars by observing how their positions shifted according to the background of more distant stellar objects.

Using parallax in conjunction with microlensing events works slightly differently, with separated observers relying on precisely synchronized clocks to measure the differences in time between their observations of the event. This time delay then allows observers to calculate the distance to the lensing exoplanet as well as its mass and size.

"CLEoPATRA would be at a great distance from the principal observatory, either Roman or a telescope on Earth," Barry said in a NASA press release. "The parallax signal should then permit us to calculate quite precise masses for these objects, thereby increasing scientific return."

The benefit in spotting rogue exoplanets isn't just increasing the already burgeoning exoplanet catalog. Exploring these worlds could also teach us more about how the planets in our solar system, including Earth, formed and evolved.

"We want to find multiple free-floating planets and try to obtain information about their masses, so we can understand what is common or not common at all," research assistant at Goddard and Ph.D. student at the Catholic University of America in Washington, Stela Ishitani Silva, said. "Obtaining the mass is important to understanding their planetary development."

If all goes according to plan, CLEoPATRA will launch on a Mars mission around the same time as the launch of the Nancy Grace Roman Space Telescope currently set for the mid-2020s.

"CLEoPATRA will permit us to estimate many high-precision masses for new planets detected by Roman and PRIME," said Barry. "And it may allow us to capture or estimate the actual mass of a free-floating planet for the first timenever been done before. So cool, and so exciting. Really, it's a new golden age for astronomy right now, and I'm just very excited about it."

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NASA to Use Artificial Intelligence to Discover Rogue Exoplanets Wandering the Galaxy - Newsweek

In a world that is expanding by the second into a stuffier, more polluted version of its former self, there are few experiences that match the pleasure of a beautiful starry sky. With crisp clean air as your companion, a new observatory in the hilly state of Uttarakhand is now offering respite from the cacophony of metropolitans.

Starscapes Experiences Pvt Ltd, a chain of observatories in the country, has launched its second public observatory in Uttarakhand. The Stargate Observatory is located in Bhimtal and has already received rave reviews. Their first public observatory was set up in Kasauni.

Bhimtal, a small town about 22kms away from Nainital, is immensely popular with tourists who often come searching for unique historical sites as well as the iconic Bhimtal lake. With beautiful Himalayan hills surrounding the quiet place, Bhimtal is ideal for a night of stargazing. A 7-hour drive from Delhi, the observatory promises to be a hotspot for those who wish to unravel the mysteries of the sky under the night light.

RELATED:Stargazing in the Hills

The new observatory will offer tourists a holistic astronomical experience, with the Night Show being the observatory's main attraction. Experiences on offer also include sun observations and audio visual shows of the night sky.

From stargazing safari to astrophotography, Stargate Observatory Bhimtal will offer an integrated astronomy experience to travel enthusiasts.

The observatory also has an in-house store that offers merchandise related to astronomy, and helps tourists rediscover the universe in a new light.

With experienced guides to hand hold you through the process, the observatory is sure to add to the growing popularity of Nainital and its neighbouring towns.

READ:This Tiny Country in the Pacific is the Best Place to Watch the Night Sky

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You Can Now Head to Uttarakhand for a Date with the Night Sky - Outlook India

In astronomy, like with most fields of science, there are mysteries we run across we cant explain. In movies and TV show this usually means some extremely weird phenomenon thats about to fall from the sky or break out of a beaker and wreak havoc, and the scientist in the story has no idea why.

In real life though the mystery is usually a little less life-threatening and more of a Huh. I wonder whats going on here? kind of a thing. And the problem isnt that we dont have an explanation, its that we have too many and cant be sure which is to blame.

For example, I present to you the jaw-droppingly gorgeous but somewhat mystifying galaxy NGC 2276, as seen by the Hubble Space Telescope:

Oooooo. So pretty. But also (cue creepy music) verrrryyyyy myseteeeeerious.

OK, cut the music. The mystery isnt creepy, but it is a head scratcher. NGC 2276 is a spiral galaxy, but its distorted, lopsided. Theres an obvious central bulge to it, like most spirals have, but weirdly the bulge isnt central. Its way off to the side (to the west, in this case).

Clearly something big and powerful has exerted a strong force on this galaxy, changing its shape. But what?

As it happens, theres a big galaxy not too far from NGC 2276, a puffy elliptical one called NGC 2300. Elliptical galaxies tend to be shaped like cotton balls and can be spherical or highly elongated, and can get very large, far larger than typical spiral.

So they have powerful gravity, and we know that when two galaxies get close to each other their gravity can distort the other, warping their shapes. Youll notice that the distortion in the spiral is on the side closest to the elliptical, too, so that fits.

Also, X-ray and radio wave images of NGC 2276 also show what appears to be tails of hot and cold gas (what are called tidal tails) extending toward NGC 2300 as well.

So, case closed, right?

Yeah, well, hang on a sec.

Take another look at that wide view of NGC 2276. Pinkish/red regions are gigantic gas clouds churning out stars. They seem to be clustered more around the upper left (east) side of the galaxy, on the side facing away from the elliptical. Thats odd; tides wouldnt do that. Its more like the gas on the left side of the galaxy is being compressed when that happens the gas clouds collapse and for lots of stars. The stars then light up the gas, which is why that side appears brighter.

Not only that, but there have been an unusual number of supernovae, exploding stars, in NGC 2276 in the past few decades, and at least two of them were on the left side. Also, detailed X-ray images show lots of extremely bright sources of high-energy light for there, two. That may be from black holes gobbling down matter from a companion star, and those black holes would have formed from massive stars exploding as supernovae. Massive stars are rare (you get like one out of every few hundred or thousand stars made). Lots of massive stars indicates lots of star birth, again implying the left/east side of the galaxy is being compressed.

So how can that gas get compressed? The easiest and most common way is for a galaxy to be moving through gas outside of it; the pressure from that gas as the galaxy rams through it blows away the gas inside the galaxy (for a fun analogy involving cars and gassy dogs, try here).

That kind of intergalactic gas usually exists in big galaxy clusters, ones with hundreds or thousands of galaxies in them. NGC 2276 isnt in a cluster like that.

but it is in a group of galaxies, a small clutch of a few dozen galaxies, centered on NGC 2300, the elliptical! These are much smaller collections of galaxies, and its been thought that they dont have enough gravity to hold on to very much gas. Our Milky Way is in a group (called the Local Group; dont get me started on how astronomers name things), and theres very little gas in it.

However, a deep X-ray image of the NGC 2300 Group taken by the ROSAT observatory does show that theres hot gas in the group, and it is in fact enough to exert pressure on NGC 2276 as it plows through it.

A pair of studies (one in 2006 and another in 2015) looking at how effective this type of pressure is on NGC 2276 showed that not only is it possible that the ram pressure is whats distorting the galaxy, its easily strong enough to do so without any tidal stretching by NGC 2300!

So its not so much that the bigger elliptical galaxy is pulling on NCG 2276 and stretching it out to the right, its more that NGC 2276 is moving rapidly enough that the gas between galaxies is compressing it on the left.

Mystery solved!

Well, maybe. Its pretty rare in astronomy that any one cause is making all the effects seen. Its still possible theres some tidal distortion from the elliptical, and who knows what else might be going on. We can state with some confidence that gas compression is the major effect here, but maybe not everything. Also, it's likely that due to this pressure NGC 2276 will lose its remaining gas in the next two billion years or so.

So its nice to at least be able to know that much. And it does show that galaxy groups can retain decent amounts of gas, which is an important bit of knowledge. If we dont see it in our own group, why not? Is the NGC 2300 group an exception or are we?

And thats very typical for astronomy: Answer one questions, get a bunch more. The Universe is a complicated place, which makes it that much more fun when you figure out a piece of it.

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This lopsided galaxy is a mess. But why? - SYFY WIRE

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Project coordinator: Fabien ChreauGraphic designer: Johan Meuris, Martn BernardiDeveloper: Alexander Wolf, Guillaume Chreau, Georg Zotti, Marcos CardinotContinuous Integration: Hans LambermontTester: Khalid AlAjajiand everyone else in the community.

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Every decade the United States astronomy community comes together to debate the future of their scientific field. With limited resources, both in research funding and time, astronomers decide what questions they are most interested in pursuing and recommend telescopes that can help them answer those questions. Its a process by astronomers, for astronomers, but their decisions are primarily funded through federal dollars and lead to scientific discoveries and images, which make their way into public discourse. The Hubble Space Telescope and its breathtaking views of the universe exist in part because of this practice, called the Decadal Survey on Astronomy and Astrophysics. The National Academy of Sciences is due to release their updated Decadal Survey later this year, and the astronomy community anxiously awaits to see the latest recommendations from a 50-plus year process that has led to some of the most groundbreaking and iconic projects in modern astronomical history.

This image, taken with the Hubble Space Telescope, is packed with a cluster of galaxies along with a few foreground stars. Hubble received priority status in the 1970s Decadal Survey, was funded, and became the first of NASAs Great Observatories to be launched into space. (ESA/Hubble & NASA, F. Pacaud, D. Coe)

It takes more than one type of telescope to observe all the light and information streaming towards Earth from the near and distant universe. This means that different astronomical questions rely on different types of telescopes to answer them. Want to study planets orbiting other stars? Youll get the best data flying a telescope on a plane in the high Earth atmosphere or, better yet, launching a telescope into space. Want to study supernovae? The high energy gamma rays created by a supernova explosion can only be studied directly with a space telescope that uses special detectors. How about neutrinos? These elusive particles that can help astronomers discover the sources of cosmic rays are best studied with observatories built deep beneath Earths surface. Each area of research requires building very different observatories so astronomers must choose where they want to focus their efforts.

Telescopes are designed to measure different types of light and are often placed above Earths atmosphere, which blocks many types of light from reaching the surface. (STScI/JHU/NASA)

Through the process of prioritizing astronomical questions and instruments, the Decadal Survey serves as a recommendation to Congress on where federal money should be allocated to NASA for astronomical research. Large observatories, whether they are located underground, built on a tall mountain, flown through the atmosphere, or launched into space, are expensive endeavors and take years of development and construction. Because of these constraints, astronomers often have to decide if they prefer several small and mid-range telescopes or one or two extremely large telescopes. In addition to prioritizing future research topics and the required instruments of those projects, astronomers also consider the current state of previously constructed observatories.

The first three decadal surveys prioritized a suite of space-based telescopes that covered the universe from the infrared to gamma rays. These four space telescopes became known as NASAs Great Observatories and have been the bedrock for astronomical research in space for the last 30 years. The 1970 report prioritized what became the Hubble Space Telescope and a series of high energy astrophysical observatories, which led to the development of the Compton Gamma Ray Observatory. The 1980 report prioritized the Chandra X-ray Observatory and, in the 1990s, the Spitzer Space Telescope and infrared astronomy received the highest ranking.

This image of spiral galaxy M101 is a composite of data from three of NASAs Great Observatories. Chandras X-ray data (top right) is shown in blue, Hubbles optical data (middle right) in yellow, and Spitzers infrared data (bottom right) in red. Combined these observatories create a more detailed look of the universe. (NASA/JPL-Caltech/ ESA/STScI/K. Gordon /CXC/JHU/K.Kuntz et al.)

In the 2000 and 2010 Decadal Surveys, astronomers focused on continued pressing questions in astronomy, most notably: How did galaxies evolve from birth? How do planetary systems form and evolve? What is dark energy? Where are the potentially habitable planets? Two of the space telescopes prioritized were the Next Generation Space Telescope, now called the James Webb Space Telescope (JWST), and the Wide-Field Infrared Telescope, now called the Nancy Grace Roman Space Telescope. The 2000 and 2010 Decadal Surveys also established a stronger collaboration with international partners in effort to coordinate large-scale projects that are too costly for the U.S. to carry out on its own, a crucial element for JWST, whose budget has increased significantly since its start. After several delays, JWST is currently scheduled to launch in December 2021, after which astronomers hope to fulfill the Decadal Surveys expectation and make discoveries that will rival those of the Hubble Space Telescope when it was first launched. The Roman Space Telescope is scheduled to be launched in 2025.

Engineers completed final tests of the James Webb Space Telescope at Northrop Grumman facilities in California. The tennis court-sized sunshield was folded and stored. This was the final stop before being shipped to the launch site in Kourou, French Guiana, along the northern coast of South America. (Northrop Grumman)

Astronomers proposed four space telescopes for consideration in the 2020s Decadal Survey:

Each telescope has its strengths, but together they have the potential to form what astronomer Grant Tremblay calls the New Great Observatories. Chances are low that the Decadal Survey will recommend pursuing all four telescopes together, but each poses a unique view of the many mysteries of the universe.

The Lynx X-ray Observatory is one of the four NASA Strategic Mission concepts under consideration by the 2020 Decadal Survey. If funded and developed, Lynx promises to transform our understanding of black holes, the evolution of galaxies, and supernova. (Grant Tremblay, CC-BY-SA-4.0)

The Decadal Survey on Astronomy and Astrophysics holds immense power in directing future research and discovery. These recommendations to NASA have resulted in budget requests and approvals that have led to huge advances in astronomical research and instrumentation. After the 2020 Decadal Survey is released and prioritizations are made, the next stage of development can begin, where one or more of these telescopes is launched into space in the coming decades.

Concept art of the James Webb Space Telescope. (NASA)

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The Great Observatories: Directing the Future of Astronomical Research - National Air and Space Museum