Astronomers have compiled 15 years’ worth of data from the Sloan Digital Sky Survey into an interactive map of the observable universe.
The map includes hordes of cosmic objects, like luminous blue quasars and red elliptical galaxies. You can explore the map here.
“Astrophysicists around the world have been analyzing this data for years, leading to thousands of scientific papers and discoveries,” said Brice Ménard, an astrophysicist at Johns Hopkins University and the map’s creator, in a university release. “But nobody took the time to create a map that is beautiful, scientifically accurate, and accessible to people who are not scientists. Our goal here is to show everybody what the universe really looks like.”
The observations from a telescope in New Mexico capture about 200,000 galaxies, each filled with billions of stars and unknown worlds. The data includes many more objects than the 200,000 displayed, but if the researchers showed them all, the map would be an unnavigable sea of dots.
In that way, the map is a simplification, but the alternative would simply be overwhelming. The Milky Way—the galaxy 100,000 light-years across that we call home—is just a single pixel at the base of the map.
New Interactive Map Offers Scroll Through Universe
In theory, the underlying data for the map (and thus, the map itself) may include some of the 40-quintillion odd black holes that are estimated to be in the observable universe. Of course, black holes are so gravitationally intense that light can not escape them, so they don’t show up as light sources in the map. But quasars—very bright galactic cores—are powered by supermassive black holes at their centers, and those are visible in the map.
“We are used to seeing astronomical pictures showing one galaxy here, one galaxy there or perhaps a group of galaxies,” Ménard said. “But what this map shows is a very, very different scale.”
Users can scroll up on the map, essentially traveling back in time to see older, more red-shifted objects. A ticker on the bottom of the map shows how far back in time the user is at any given point.
Unfortunately, you can’t click on individual galaxies to figure out what (or where) they are. But nonetheless, the map serves its purpose: showing just how small and new we are in comparison to the history of the universe and all its cosmic contents.
More: The World’s Largest Digital Camera Is Almost Ready to Look Back in Time
The International Liquid Mirror Telescope in its building in the Himalayas.Photo: Jean Surdej
High in the Himalayas, a new telescope is set to observe the night sky. The contraption has a 4-meter (13-foot) lens, but here’s the kicker: it’s made of liquid mercury, a material seldom used for astronomical imaging.
Called the International Liquid Mirror Telescope (ILMT for short), the device’s main component is a layer of liquid mercury that floats on a very thin layer of compressed air. The quicksilver rotates, taking on a parabolic shape in the process—useful for focusing light from the night sky. By placing a camera at the focal point of the paraboloid, astronomers will then be able to image objects in the sky.
At first glance, the telescope’s mirror appears to be an ordinary reflective surface. But, in actuality, it’s made of liquid that was meticulously shipped up the mountain by a company that specializes in hazardous materials. As long as no one tries to drink the telescope’s mirror, though, it’s perfectly safe—and according to the ILMT team, an affordable alternative to other telescope mirror materials.
“The main advantage is the relatively low cost of a large liquid mirror compared to a large conventional telescope mirror,” said Paul Hickson, an astronomer at the University of British Columbia who works on liquid mirror technologies, in an email to Gizmodo. “As an example, the cost of the ILMT is about one tenth that of the 3.6 metre [11.8-foot] Devasthal Optical Telescope — a conventional telescope of about the same size and located at the same place.”
And that place is pretty lofty. The telescope sits over 8,000 feet above sea level on India’s side of the Himalayas. It will scrutinize a strip of sky directly overhead that contains hundreds of thousands of galaxies and several thousand quasars, Hickson said. (Quasars are very active galactic cores, which are bright in the night sky.)
By imaging the sky nightly—directly overhead, where there is the least atmospheric noise—astronomers can deduce what objects are changing in the sky over time, whether they be new supernovae, asteroids passing in front of luminous objects, or even transiting black holes bending the light from sources behind them.
“We have estimated that 50 new cases of multiply imaged quasars should be detected in the field of view of the ILMT,” said Jean Surdej, an astrophysicist at the University of Liège in Belgium and the project director, in an email to Gizmodo.
The telescope saw its first light in April, but scientific observations won’t begin until later this year. When fully operational, the telescope will collect 10 gigabytes of data nightly. Given the mercurial nature of supernovae and gravitational lenses, it’s fitting that the ILMT will captured those events with quicksilver.
Two views of the region near where the newly discovered planet was found, the one on the left from Kepler and the one on the right from the Canada-France-Hawaii Telescope (CFHT).Image: NASA/Kepler/CFHT
An exoplanet with distinctly Jupiter-like characteristics has been discovered in old data gathered by NASA’s Kepler space telescope. Remarkably, Kepler made the observation using gravitational microlensing, in what is a first for a space-based observatory.
The new research is set to be published in Monthly Notices of the Royal Astronomical Society, and it describes K2-2016-BLG-0005Lb, an extrasolar planet with roughly the same mass as Jupiter and orbiting at a position comparable to Jupiter’s distance from our Sun. Data gathered by Kepler in 2016 was key to the detection. A preprint of the study is available at the arXiv.
“This discovery was made using a space telescope that was not designed for microlensing observations and, in many ways, is highly sub-optimal for such science,” the scientists, led by PhD student David Specht from the University of Manchester, wrote in the paper. “Nonetheless, it has yielded a direct planet-mass measurement of high precision, largely thanks to uninterrupted high observing cadence that is facilitated by observing from space.”
K2-2016-BLG-0005Lb is “the first bound microlensing exoplanet to be discovered from space-based data,” the scientists say. Indeed, Kepler managed to spot over 2,700 confirmed exoplanets during its illustrious nine-year career (the mission ended in 2018), but this marks the first time that Kepler, or any space-based telescope for that matter, managed to spot an extrasolar planet through a microlensing event.
Predicted by Albert Einstein, gravitational microlensing is a kind of cosmic magnifying glass that allows astronomers to see exaggerated views of celestial objects that would otherwise be obscured by foreground objects, such as stars. Heavy objects cause light to bend over vast distances. This allows astronomers to see the light from a background star from our vantage point, as the light curves around the foreground object.
“Planets magnify starlight only whilst they are almost perfectly lined up with a background star,” Eamonn Kerins, a co-author of the study and principal investigator for the Science and Technology Facilities Council, wrote to me in an email. “Roughly only one in 100 million stars in our galaxy have their light visibly distorted by the gravitational field of planets. And when the distortions happen, they are very brief, lasting a few hours to maybe a day.”
Kerins said these sorts of signals are very difficult to detect, as astronomers need to survey the brightness of many millions of stars every few months, sometimes for years. They then have to parse through vast amounts of data in hopes of finding the signals. Kepler, which relied on the transit method to spot exoplanets (in which the periodic dimming of stars is indicative of planets passing in front of them), wasn’t really built for this.
“The main problem with Kepler is that its camera has big pixels that give us a kind of Minecraft view of the inner galaxy. All the stars look really blocky, and there are many of them in each pixel,” Kerins explained. “The key was to model very accurately how Kepler’s pixels respond in very crowded star fields. Most of the stars in the field don’t vary, so we can inspect Kepler’s camera behaviour with those stars to construct the clearest possible signal from the lensed star that is varying.” To which he added: “It was tough!”
The astronomers were looking at Kepler data from 2016, specifically data from Campaign 9 of the Kepler K2 mission. A new search algorithm flagged five candidate microlensing signals from the dataset (as revealed in research from 2021), one of which—spotted near the galactic bulge—was found to be a “clear” microlensing event, according to the new study.
It just so happens that five—yes five—ground-based surveys were scanning the same location in space at the same time, namely the Optical Gravitational Lensing Experiment (OGLE-IV), the Canada–France–Hawaii Telescope (CFHT), Microlensing Observations in Astrophysics (MOA-2), the Korean Microlensing Telescope Network (KMTNet), and the United Kingdom InfraRed Telescope (UKIRT). The data from these observatories was used to corroborate the Kepler data and further characterize the Jupiter-like planet. These campaigns were looking at the right spot at the right time, but “none of the ground-based surveys flagged K2-2016-BLG-0005 in advance” of the 2021 study, the scientists write.
The newly spotted exoplanet is 17,000 light-years from Earth. It’s practically got the same mass as Jupiter and a similar orbit in terms of distance to its host star. This planet is “one of the closest cousins to Jupiter that has so far been found by any method,” said Kerins. “It’s also almost twice as far from us as the next furthest of the thousands of planets found by Kepler,” he said, adding that “by using this new method, we’ve been able to massively extend Kepler’s reach.”
Kepler is no longer around, but NASA’s upcoming Nancy Grace Roman Space Telescope, scheduled to launch later this decade, is specifically being built to find planets using microlensing. Kerins is hopeful that the Roman telescope will reveal the planetary architectures of other star systems and the abundance of potentially habitable worlds in the Milky Way, among other things. “It’s going to be a great ride,” he said.
A Starlink satellite streak appears in a ZTF image of the Andromeda galaxy, as pictured on May 19, 2021. Image: ZTF/Caltech
Researchers at the Zwicky Transient Facility in California have analyzed the degree to which SpaceX’s Starlink satellite constellation is affecting ground-based astronomical observations. The results are mixed.
The new paper, published in The Astrophysical Journal Letters and led by former Caltech postdoctoral scholar Przemek Mróz, offers some good news and some bad news. The good news is that Starlink is not currently causing problems for scientists at the Zwicky Transient Facility (ZTF), which operates out of Caltech’s Palomar Observatory near San Diego. ZTF, using both optical and infrared wavelengths, scans the entire night sky once every two days in an effort to detect sudden changes in space, such as previously unseen asteroids and comets, stars that suddenly go dim, or colliding neutron stars.
But that doesn’t mean Starlink satellites, which provide broadband internet from low Earth orbit, aren’t having an impact. The newly completed study, which reviewed archival data from November 2019 to September 2021, found 5,301 satellite streaks directly attributable to Starlink. Not surprisingly, “the number of affected images is increasing with time as SpaceX deploys more satellites,” but, so far, science operations at ZTF “have not yet been severely affected by satellite streaks, despite the increase in their number observed during the analyzed period,” the astronomers write in their study.
The bad news has to do with the future situation and how satellite megaconstellations, whether Starlink or some other fleet, will affect astronomical observations in the years to come, particularly observations made during the twilight hours. Indeed, images most affected by Starlink were those taken at dawn or dusk. In 2019, this meant satellite streaks in less than 0.5% of all twilight images, but by August 2019 this had escalated to 18%. Starlink satellites orbit at a low altitude of around 324 miles (550 km), causing them to reflect more sunlight during sunset and sunrise, which creates a problem for observatories at twilight.
Astronomers perform observations at dawn and dusk when searching for near-Earth asteroids that might appear next to the Sun from our perspective. Two years ago, ZTF astronomers used this technique to detect 2020 AV2—the first asteroid entirely within the orbit of Venus. A concern expressed in the new paper is that, when Starlink gets to 10,000 satellites—which SpaceX expects to achieve by 2027—all ZTF images taken during twilight will contain at least one satellite streak. Following yesterday’s launch of a Falcon 9 rocket, the Starlink megaconstellation consists of over 2,000 satellites.
In a Caltech press release, Mróz, now at the University of Warsaw in Poland, said he doesn’t “expect Starlink satellites to affect non-twilight images, but if the satellite constellation of other companies goes into higher orbits, this could cause problems for non-twilight observations.” A pending satellite constellation managed by OneWeb, a UK-based telecommunications firm, will orbit at an operational altitude of 745 miles (1,200 km), for example.
Launch of a SpaceX Falcon 9 rocket with 49 Starlink satellites on board, as imaged on January 18, 2022. Photo: SpaceX
The researchers also estimated the fraction of pixels that are lost as a result of a single satellite streak, finding it to be “not large.” By “not large” they mean 0.1% of all pixels in a single ZTF image.
That said, “simply counting pixels affected by satellite streaks does not capture the entirety of the problem, for example resources that are required to identify satellite streaks and mask them out or the chance of missing a first detection of an object,” the scientists write. Indeed, as Thomas Prince, an astronomer at Caltech and a co-author of the study pointed out in the press release, a “small chance” exists that “we would miss an asteroid or another event hidden behind a satellite streak, but compared to the impact of weather, such as a cloudy sky, these are rather small effects for ZTF.”
SpaceX has not responded to our request for comment.
The scientists also looked into the measures taken by SpaceX to reduce the brightness of Starlink satellites. Implemented in 2020, these measures include visors that prevent sunlight from illuminating too much of the satellite’s surface. These measures have served to reduce the brightness of Starlink satellites by a factor of 4.6, which means they’re now at a 6.8 magnitude (for reference, the brightest stars shine at a magnitude 1, and human eyes can’t see objects much dimmer than 6.0). This marks a major improvement, but it’s still not great, as members of the 2020 Satellite Constellations 1 workshop asked that satellites in LEO have magnitudes above 7.
The current study only considered the impacts of Starlink on the Zwicky Transient Facility. Every observatory will be affected differently by Starlink and other satellites, including the upcoming Vera C. Rubin Observatory, which is expected to be badly affected by megaconstellations. Observatories are also expected to experience problems as a result of radio interference, the appearance of ghost-like artifacts, among other potential issues.
More: Elon Musk Tweets Video of ‘Mechazilla’ Tower That Will Somehow Catch a Rocket.
Artist’s impression of a free-floating planet.Image: Wikimedia Commons
Data gathered by NASA’s now-retired Kepler Space Telescope has revealed a small population of free-floating planets near the Galactic Bulge. The new finding raises hope that a pair of upcoming missions will result in further detections of unbound planets, which drift through space separated from their home stars.
The Kepler mission ended in 2018, but its legacy continues to unfold. During its nearly 10 years of service, the famous space telescope managed to detect at least 2,245 exoplanets, with thousands yet to be confirmed. We can now add four new candidate planets to the list, but these aren’t of the typical variety. They’re unbound, meaning they’re not in orbit around any star.
Rogue planets, are they’re informally known, likely formed from a protoplanetary disc around a host star but were then tossed out into interstellar space by the gravitational perturbations of larger planets. These wanderers range in size from Earth-like through to Jupiter-scale behemoths. Fascinatingly, they might be exceptionally abundant, with some scientists estimating trillions of them in the Milky Way. Their true population size remains a mystery, however.
In new research published today in Monthly Notices of the Royal Astronomical Society, a team of astronomers presented their analysis of data gathered during the Kepler K2 mission. The group was led by Iain McDonald, a lecturer in astrophysics at the Open University and a research fellow at the University of Manchester. The paper describes how, from late April to early July 2016, Kepler periodically gazed upon a large cluster of stars located near the Galactic Bulge as it hunted for gravitational microlensing events.
As Einstein famously predicted, foreground objects can warp the light emanating from background stars. This results in the temporary magnification of the incoming light from our perspective, and the effect can last from just a few hours to a few days. Microlensing events are relatively rare, and those produced by rogue planets are even rarer.
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As McDonald explained in an email, he and his team performed the study because they wanted to find out how many rogue planets might exist, as past studies tend to vary in terms of estimates.
“Free-floating planets are the ruins of the formation of planetary systems where the orbits of planets and stars were incompatible,” wrote McDonald. “The number of free-floating planets we see tells us how violent the process of making planets normally is.”
Importantly, a special data reduction technique was needed for this research, as Kepler wasn’t designed to detect planets with microlensing events. More common for the space telescope is to find exoplanets using the transit method, in which a passing exoplanet causes a noticeable dimming in its host star.
“Scientists are often challenged to find new uses for old equipment,” said McDonald. “In this case, it involved five years’ work from two people,” namely Radek Poleski, a co-author of the study and an astronomer at the University of Warsaw, and McDonald himself. Poleski’s contribution allowed the team to obtain the best measurements of a star’s brightness from the ailing Kepler telescope, while McDonald’s work resulted in a tailor-made technique for “searching over 12 billion measurements of stars’ brightnesses for events that could be free-floating planets,” he explained.
Looking at the Kepler K2 data, the scientists documented dozens of short-duration microlensing events near the galactic core. Of these, 22 were previously detected during the OGLE and KMTnet ground-based campaigns, but five signatures hadn’t been seen before. Of these five, one turned out to be a bound exoplanet, but the remaining four featured super-short microlensing events consistent with free-floating planets. One of the four candidate signatures was subsequently detected in ground-based data. The microlensing events, lasting for just several hours, suggest the discovery of unbound exoplanets no larger than Earth. These four events have been designated candidate free-floating planets, because astronomers cannot go back and look at them again, as McDonald explained.
“They are too faint to see directly, and unlikely to ever microlens another star on human timescales, so we can’t prove definitively that these are free-floating planets,” he wrote. “Instead, what we have had to do is rule out every other scenario we can think of. We have tried to rule out problems with [Kepler and its instruments], bodies in our solar system like asteroids, pulsating and other kinds of variable stars, and flares on stars with strong magnetic fields. The only likely explanation we were left with is free-floating planets.”
It’s impossible to know what the conditions are like on these presumed rogue exoplanets, but McDonald said they could be “cold, icy wastelands,” and, if similar in size to Earth, their surfaces would “closely resemble bodies in the outer Solar System, like Pluto.”
The new paper suggests the presence of a large population of Earth-sized rogue planets in the Milky Way. It’s becoming clear that free-floating planets are common. McDonald said his team is currently working to come up with a more precise estimate for how many of them might exist.
The new research also shows that free-floating planets can be detected with current telescopes. That said, NASA’s Nancy Grace Roman Space Telescope and ESA’s Euclid mission are poised to discover even more.
“The Roman and Euclid missions are much more powerful telescopes than Kepler and will be much more stable,” McDonald explained. “Plans exist to point these telescopes at the same patch of sky and look for other free-floating planets. Finding these planets with Kepler gives us confidence that this is a good use of the limited time that we will be able to use Roman and Euclid for, and lets us hone how we will perform those observations to make the best detections.”
If rogue planets really are abundant, the aforementioned missions should have no difficulty in finding them. It’s only a matter of time before we know more about these celestial nomads.
More: Warped light reveals smallest rogue planet known to science.