Observing billions of galaxies across more than a third of the sky and building a 3D map of the universe are all part of the Euclid mission that the European Space Agency launched with its Euclid satellite from Cape Canaveral, Florida. Euclid’s dataset is getting a big helping hand from observations taken at three observatories in �鶹��ý.

The Euclid satellite mission will spend more than six years in space and involve more than 2,000 scientists, including astronomers in �鶹��ý. Unlike the James Webb Space Telescope, which observes a tiny portion of the universe in great detail, Euclid will survey a large portion of the sky, to see a massive section of the universe.

Prior to Euclid’s launch, the work of creating the map began in �鶹��ý through the project, an ambitious imaging survey of the northern sky in the optical and near-infrared conducted by three �鶹��ý-based telescopes since 2017: the Canada-France-�鶹��ý Telescope (CFHT), Japan’s Subaru Telescope on Maunakea, and the University of �鶹��ý (IfA) Pan-STARRS telescope on Haleakalā, Maui.

UNIONS is co-led by Jean-Charles Cuillandre of CEA Saclay/Université Paris-Saclay, along with Ken Chambers at IfA, Alan McConnachie at Dominion Astrophysical Observatory (DAO) in Canada, Oguri Masamune at Chiba University in Japan, and Mike Hudson at the University of Waterloo in Canada.

“The superb observing conditions in �鶹��ý led to the unprecedented collection of galaxies over a very large area of the sky with each telescope playing a critical role by adding different filters or colors to the Euclid data,” said Cuillandre, a former CFHT staff astronomer. “While a critical part of the original motivation to obtain the UNIONS data was the Euclid mission, the data will have an impact extending far beyond the space mission.”

The IfA team is especially interested in using this data to measure the parameters that characterize the properties of the universe.

“The Euclid mission will provide a next generation measurement of these characteristics, and we may discover we have made a mistake or series of small mistakes along the way, or we may find that dark energy is more complicated than in Einstein’s formulation,” said Chambers. “Or there might be something else, some new aspect of the universe that we are presently unaware of.”

�鶹��ý adds color

By observing more than one-third of the observable sky outside the Milky Way, Euclid will image billions of targets out to a distance of 10 billion light years. Astronomers estimate the distances to these galaxies—and thus convert 2D images to a 3D map of the universe—using their observed brightness in different color filters. The more filters are used, the better the distance estimate. But Euclid has only four filters—one that spans most of what we see as visible light, and three that cover infrared wavelengths, beyond what our eyes can see.

The �鶹��ý telescopes will add observations in five visible-light filters, spanning the rainbow from the violet to far-red. In other words, the three �鶹��ý telescopes turn the black and white 2D images from Euclid into a full color, 3D map of the universe. Because Euclid is mapping such a huge swath of sky, and ground-based telescopes have different capabilities, multiple observatories have to contribute to provide all the data.

“The idea for one filter from space and additional filters from ground-based telescopes was the Euclid plan from the beginning. Subaru observations add far-red and green, Pan-STARRS has been observing the sky for years searching for asteroids allowing a depth of red data, and CFHT adds blue, enhancing the one filter images that Euclid will produce,” said Professor Satoshi Miyazaki, director of Subaru Telescope. “UNIONS is a consortium of telescopes in �鶹��ý, extending broader than just Euclid. UNIONS scientists are also sharing data to conduct research collaborations based on �鶹��ý.”

Gravitational lensing

“Ultimately, data from the �鶹��ý telescopes—CFHT, Subaru, and Pan-STARRS—will turn the images into a three-dimensional map of our Universe.”

Dark matter does not emit light like the more familiar planets, stars and galaxies. However, dark matter has gravity and can be detected by observing large clusters of galaxies. In some cases, the immense gravity of a galaxy or cluster of galaxies can bend light from an object behind it, known as gravitational lensing. Ground-based observations will assist astronomers working on the Euclid gravitational lensing project.

“I have worked on the Euclid mission for 12 years and it is very satisfying to see the mission launch,” said Jean-Gabriel Cuby, CFHT executive director and Euclid board member. “Much like with the James Webb Space Telescope, Euclid will surprise us and lead to insights we do not fully anticipate. Insights enabled by the efforts of the teams at CFHT, Subaru and Pan-STARRS.”

The first images from the Euclid mission are expected in around two months. Euclid will build up a large archive of unique data, unprecedented by volume for a space-based mission, enabling research over all disciplines in astronomy. The data will be archived at the Canadian Astronomy Data Center (CADC) and accessible to astronomers around the world. CADC will also provide color information based on the observations from the �鶹��ý based telescopes.

“The Euclid images will be beautiful to look at, above and beyond the considerable scientific value of the data. I’m looking forward to seeing them,” said Stephen Gwyn, science data specialist at the Canadian Astronomy Data Centre. “Ultimately, data from the �鶹��ý telescopes—CFHT, Subaru, and Pan-STARRS—will turn the images into a three-dimensional map of our Universe.”

Mysteries have swirled around the origin of interstellar object ʻOumuamua since astronomers on Haleakalā first discovered it in 2017 with the University of �鶹��ý (Panoramic Survey Telescope and Rapid Response System) telescope.

The published in Nature envisions ʻOumuamua as a water-rich comet traveling through the space between stars. Over time, ʻOumuamua was bombarded by radiation, which formed hydrogen inside the comet. As hydrogen gas released from the interstellar comet, it accelerated.

The new study speculated how hydrogen came off ʻOumuamua, which researchers wouldn’t have been able to detect. When water ice sits in space, the cosmic radiation interacts with it and produces hydrogen. When the hydrogen escaped, it created the acceleration that researchers originally observed, explaining why ʻOumuamua was accelerating, and nobody saw gas.

However, this theory does not explain the elongated shape of ʻOumuamua.

“I don’t disbelieve it, but I don’t think it is necessary to explain ʻOumuamua,” said Astronomer Karen Meech, who was the leader of the team that first characterized the object. “I think it could be just an ordinary comet. The reason people didn’t think it could be just an ordinary comet is because all of the observations we had couldn’t fit together in a nice model. But people forget that we only observed it in detail for a little over a week. I think we just didn’t have enough data to do a comprehensive model that would fit all of the observations, yet we are trying anyway.”

ʻOumuamua, originally an object from another star system, has come close enough to Earth for astronomers to study. Usually, observing objects from other star systems only provides astronomers with remote observations that do not provide many details.

“One thing that is very interesting is how much effort is going to try and explain this one. It is the first of its kind that has ever been detected, it was a �鶹��ýdiscovery which makes it exciting,” said Meech. “The level of scientific interest that has come from all directions is fascinating.”

Alien hypothesis not following scientific process

Most researchers from the scientific community can find common ground on what ʻOumuamua is. However, a Harvard professor continues to speculate that the object could be designed by an extraterrestrial intelligent civilization.

“Almost all of the scientific community thinks that it is a leftover building block from the process of forming planets,” said Meech. “There is one person who seems to be pushing the alien hypothesis. He has gone out on a limb, and now I fear he can’t back down.”

“I would’ve been happy if he had said ‘what would it take us to consider the evidence that would be necessary for us to go down the path that this is alien technology?’ That would have been okay because that is part of the scientific process,” added Meech. “But he has just outright declared that it is. The problem with that is that it is teaching students not to follow the scientific process.”

UH at the forefront

PAN-STARRS1 is the world’s leading Near Earth Object discovery telescope and is superb at
finding faint, distant comets. After finding ʻOumuamua, Meech believes that there are going to be more opportunities in the future.

“To find one without a comet tail must mean they are awfully abundant. I think UH will be at the forefront of following these things. All of the big telescopes around the world are going to go after the next one and we hope to be leading the pack here at UH.”

What does our universe look like at the largest size scales? A team of researchers from the University of �鶹��ý (IfA) and in Hungary has produced a massive new catalog of high-fidelity distance estimates to more than 350 million galaxies, revealing the soap-bubble structure of the universe in detail.

The team used data from UH’s or Pan-STARRS1 (PS1) on Haleakalā and the space-based (WISE) mission to first classify objects as stars, quasars, and galaxies, and then estimate the distances to galaxies. IfA’s Pan-STARRS1 Sky Survey data is currently the largest public imaging survey in visible light. In combination with WISE, this provides brightnesses for each object in nine different color filters and many other parameters.

• Related UH News story: Largest digital sky survey released by Pan-STARRS, December 19, 2016

IfA Astronomer István Szapudi said, “Combining the optical PS1 with the spaced-based infrared colors of WISE yields a large and homogeneous map of the universe extending out 10 billion light-years. We are seeing the structure of the universe back to when it was less than half of its present age.”

The catalog, WISE-PS1-STRM, is now available to the public on . Research was recently published in the .

In addition to the two massive datasets, the team applied special computational methods they developed to analyze object colors and shapes and extract their types and distances.

“These deep-learning tools have been refined and improved so they now produce classifications and distances that are accurate to one percent,” said Robert Beck, a former cosmology postdoctoral fellow at IfA.

According to researchers, the catalog will be useful in a vast number of scientific projects, and paves the way for similar work from future space-based projects such as Euclid, a near-infrared space telescope under development in Europe focused on researching dark energy and dark matter by accurately measuring the acceleration of the universe.

A near-Earth asteroid about the size of a Ferris wheel first detected in 2016 by the University of �鶹��ý (IfA)-operated (Pan-STARRS) may shed some light on the early Solar System. New data published in indicates (469219) Kamoʻoalewa could be a fragment of the Moon.

According to the study, the infrared spectrum of the 165-foot long object appears to match that of material found on the lunar surface. To help determine its origin, China is preparing for a spacecraft launch in 2024 in an attempt to retrieve samples from the asteroid.

“To my knowledge, this is the most promising evidence to date of an asteroid actually being a remnant from a past lunar impact,” said IfA Director Doug Simons. “The best way to determine if it is of lunar origin is a sample-and-return mission, so precise chemical analyses can be made to compare material from Kamoʻoalewa with material brought back to earth from past Apollo missions to the surface of the moon.”

More than just a name

This recent research has topped international and national headlines, such as leading astronomy publications and the New York Times where the asteroid’s Hawaiian language name is widely utilized. The use of ʻōlelo �鶹��ý (Hawaiian language) on such a large scale is both uplifting and encouraging news for UH Hilo Executive Director Kaʻiu Kimura who helped spearhead the naming of the �鶹��ý-discovered Near Earth Object through , a program where Hawaiian speaking students and educators work with �鶹��ý-based astronomers to create names in ʻōlelo �鶹��ý for objects discovered by �鶹��ý-based observatories.

“We were very encouraged to see the recent theory on Kamoʻoalewa. The students who gave the name Kamoʻoalewa put a lot of thought and energy into researching appropriate contexts,” Kimura said. “They did in fact consider that this object may have been a ‘moʻo’ or ‘offspring’ that is orbiting in our solar system. It is amazing to now see scientific theory support their keen intuition.”

• Related UH News story: Hawaiian students learn, name astronomical discoveries through ʻImiloa program, January, 8, 2019

In ʻōlelo �鶹��ý, Kamoʻoalewa alludes to a celestial object that is oscillating, like its path in the sky as viewed from the Earth. It is a name found in the Hawaiian chant Kumulipo.

A Hua He Inoa is also behind the names of five other celestial discoveries, including the headline grabbing interstellar object ʻOumuamua. The program is a collaborative effort between ʻImiloa, IfA, community members and UH �ᾱ����’s .

“As I’ve mentioned before, by naming major astronomical discoveries made from �鶹��ý, A Hua He Inoa is helping give Maunakea and Haleakalā an international voice—it is only fitting that voice is Hawaiian,” Simons explained.

Kamoʻoalewa is about 4 million times fainter than the faintest star the human eye can see in a dark sky and never gets closer than 9 million miles to Earth.

Astronomers are revelling at the discovery of a white dwarf that is the largest ever seen. White dwarfs are the collapsed remnants of stars, and this latest find is roughly the size of the Moon and 1.35 times more massive than the Sun. Researchers at the Zwicky Transient Facility at Caltech’s Palomar Observatory made the discovery. To help characterize the dead star, astronomers turned to the on Maunakea and University of �鶹��ý’s on Haleakalā, Maui.

In 2016, Pan-STARRS released the world’s largest digital sky survey enabling access to millions of images and catalogs containing precision measurements of billions of stars and galaxies. That data helped researchers estimate the temperature of the white dwarf and its radius.

“We have enabled astronomers all over the world to continue to make new discoveries,” said Ken Chambers, director of Pan-STARRS Observatories. “This discovery of a highly magnetized and rapidly rotating white dwarf, is one of many, many examples of just how scientifically useful the Pan-STARRS1 Survey has become to the scientific community.”

Using Keck Observatory’s low-resolution imaging spectrometer, the team realized the sheer power of the star’s magnetic field. According to astronomers, the white dwarf’s extreme magnetic field is almost one billion times stronger than the Sun’s and whips around on its axis at a frenzied pace.

Ilaria Caiazzo, a researcher at Caltech is the lead author of the new study based on the white dwarf. The newly discovered object’s size is also considered small in size.

“It may seem counterintuitive, but smaller white dwarfs happen to be more massive,” Caiazzo said. “This is due to the fact that white dwarfs lack the nuclear burning that keep up normal stars against their own self gravity, and their size is instead regulated by quantum mechanics.”

Researchers suspect that the merged white dwarf may be massive enough to evolve into a neutron-rich dead star, or neutron star, which typically forms when a star much more massive than our Sun explodes in a supernova.

For more information go to .

From working to determine if other planets can support life to monitoring the skies for hazardous asteroids and comets, the University of �鶹��ý (IfA) remains at the forefront of cutting edge space science.

On June 3, IfA Interim Director and Astronomer Karen Meech shared with the UH Board of Regents (BOR) Committee on Research and Innovation some of the units research accolades and the sheer impact IfA’s collaboration with observatories on Maunakea and Haleakalā has had on the astronomy field.

UH’s Pan-STARRS1 telescope on Haleakalā is the world leader in finding larger Near-Earth Objects that could pose a threat to the planet. IfA astronomers who operate the observatory on Maui play a fundamental role in the nation’s planetary defense program. In 2017, during routine operations, Pan-STARRS discovered the mysterious interstellar object, ʻOumuamua, the very first of its kind spotted in the solar system. The rapidly rotating object mesmerized researchers around the globe and left many scrambling to explain its origin and where it was headed.

“Most people don’t realize how close to Earth that came, within 63 Earth Moon distances,” said Meech during the BOR presentation. “That’s really close…Pan-STARRS was instrumental in discovering that.”

Vital Maunakea telescopes

Meech explained to the BOR committee how vital telescopes on Maunakea were in unraveling the headline-grabbing object’s mystique. In 2017, with Meech at the helm, IfA led an international research team that gathered data on ʻOumuamua and joined forces with observatories on �鶹��ý Island. “We used everything on Maunakea,” Meech said. “Every telescope was providing a unique piece of science and we had to do it fast…Everyone was willing to share. Pretty much every big telescope on planet Earth was looking at that object for a week but Maunakea did the lion’s share of the analysis.”

• Related UH News story: Mysteries of interstellar ʻOumuamua part of UH speaker series, June 7, 2021

Meech’s team ruled out theories such as ʻOumuamua could be an alien spacecraft sent from a distant civilization. They suggested the interstellar object was of natural origin and possessed similar qualities, such as its red color, to objects found within our own solar system.

Life in Space

Currently, IfA astronomers are contributing to groundbreaking research on the formation of planetary systems and habitable planets. Meech explained to the Board of Regents that IfA has teamed up with other leading astronomy facilities to expand space science in understanding how life evolves, begins and where it can exist. With potential space missions on the horizon to collect essential data, IfA foresees building satellites or telescopic instruments for research quests.

This research is an example of �鶹��ýMānoa’s goals of (PDF) and (PDF), two of four goals identified in the (PDF), updated in December 2020.

Earth has captured a tiny object from its orbit about the Sun and will keep it as a temporary satellite for a few months before it escapes. But the object is not an asteroid; it’s likely an upper stage booster rocket that helped lift NASA‘s ill-fated Surveyor 2 spacecraft toward the Moon in 1966.

University of �鶹��ý’s telescope atop Haleakalā spotted the object in September 2020. Astronomers at the NASA-funded survey telescope noticed it had an unusual motion—it followed a slightly curved path in the sky, which is a signature of it being nearby, with the curvature caused by the rotation of the observer around Earth’s axis as Earth spins. Initially assumed to be a regular space rock orbiting the Sun, it was given an asteroid-like designation: 2020 SO.

“We were pleased to discover this object via its slightly curved motion, even though it was of artificial origin,” said Astronomer Richard Wainscoat, who leads Near-Earth Object observations at Pan-STARRS. “We hope this technique will lead to further interesting discoveries of nearby objects, especially asteroids that might be temporarily captured into Earth’s orbit.”

But scientists at the at NASA‘s Jet Propulsion Laboratory in Southern California saw the object’s orbit and suspected it was anything but a normal asteroid.

Most asteroids’ orbits are elongated and tilted relative to ours. But 2020 SO was moving slowly and following a nearly circular orbit around the Sun, closely matching that of Earth’s. In addition, the object’s orbital plane almost exactly matched that of our planet—highly unusual for a typical asteroid.

As astronomers at Pan-STARRS and around the world made additional observations of 2020 SO, the data also started to reveal the degree to which the Sun’s radiation was influencing 2020 SO‘s trajectory—an indication that it may not be an asteroid at all but a suspected rocket booster.

Space Age artifact

The lunar lander was launched toward the Moon on Sept. 20, 1966, on an Atlas-Centaur rocket. The mission was designed to reconnoiter the lunar surface ahead of the Apollo missions that led to the first crewed lunar landing in 1969. Shortly after lift-off, Surveyor 2 separated from its Centaur upper stage booster rocket as intended. But it lost control a day after launch when one of its thrusters failed to ignite, throwing the spacecraft into a spin. The spacecraft crashed into the Moon just southeast of Copernicus crater on September 23, 1966. The discarded Centaur upper stage rocket, meanwhile, sailed past the Moon and disappeared into an unknown orbit about the Sun.

Now, in 2020, the Centaur appears to have returned to Earth for a brief visit. Before it leaves, it will make two large loops around our planet, with its closest approach on December 1. During this period, astronomers will get a closer look and confirm if 2020 SO is indeed an artifact from the early Space Age.

A team of international asteroid and comet experts now agree that ʻOumuamua, the first recorded interstellar visitor, has natural origins, despite previous speculation by some other astronomers that the object could be an alien spacecraft sent from a distant civilization to examine our star system.

A review of all the available evidence by an international team of 14 experts, including Robert Jedicke and Karen Meech of the University of �鶹��ý’s (IfA), strongly suggests that ʻOumuamua has a purely natural origin. The research team reported its findings in the July 1, 2019, issue of Nature Astronomy.

“While ʻOumuamua’s interstellar origin makes it unique, many of its other properties are perfectly consistent with objects in our own solar system,” said Jedicke. ʻOumuamua’s orbit and its path through our solar system matches a prediction published in a scientific journal by Jedicke and his colleagues half a year before ʻOumuamua’s discovery.

“It was exciting and exhausting to coordinate all the ʻOumuamua observations with my co-authors from all around the world,” said Meech. “It really was a 24-hour-a-day effort for the better part of two months. In that paper we established that ʻOumuamua rotates once in about seven hours and that it had a red color similar to many objects locked within our own solar system.”

The work showed that ʻOumuamua must have an extremely elongated shape, like a cigar or maybe a frisbee, unlike any known object in our solar system based on changes in its apparent brightness while it rotated.

UH team provides essential analysis

Meech and other UH researchers were essential to another paper published in Nature a year ago that indicated ʻOumuamua is accelerating along its trajectory as it leaves our solar system. This behavior is typical of comets but astronomers have found no other visual evidence of the gas or dust emissions that create this acceleration.

• Related UH News story: An interstellar visitor unmasked, November 20, 2017

“While it is disappointing that we could not confirm the cometary activity with telescopic observations, it is consistent with the fact that ʻOumuamua’s acceleration is very small and must therefore be due to the ejection of just a small amount of gas and dust,” Meech explained.

“We have never seen anything like ʻOumuamua in our solar system,” said Matthew Knight of the University of Maryland. “Our preference is to stick with analogs we know, unless, or until we find something unique. The alien spacecraft hypothesis is a fun idea, but our analysis suggests there is a whole host of natural phenomena that could explain it.”

Team assessment

The team of astronomers hailing from the U.S. and Europe met late last year at the International Space Science Institute (ISSI) in Bern, Switzerland, to critically assess all the available research and observations on ʻOumuamua and will meet again later this year. Their first priority was to determine whether there is any evidence to support the hypothesis that ʻOumuamua is a spacecraft built by an alien civilization.

“We put together a strong team of experts in various different areas of work on ʻOumuamua. This cross-pollination led to the first comprehensive analysis and the best big-picture summary to date of what we know about the object,” Knight explained. “We tend to assume that the physical processes we observe here, close to home, are universal. And we haven’t yet seen anything like ʻOumuamua in our solar system. This thing is weird and admittedly hard to explain, but that doesn’t exclude other natural phenomena that could explain it.”

• Related UH News story: Is the interstellar asteroid really a comet?, June 27, 2018

The ISSI team considered all the available information in peer-reviewed scientific journals and paid special attention to the research published by IfA researchers. In particular, Meech’s research paper in the journal Nature first reported on ʻOumuamua’s discovery and characteristics in December 2017, just two months after the unusual object was identified by Pan-STARRS1 (Panoramic Survey Telescope and Rapid Response System) on Haleakalā.

The ISSI team considered a number of mechanisms by which ʻOumuamua could have escaped from its home system. For example, the object could have been ejected by a gas giant planet orbiting another star. According to this theory, Jupiter created our own solar system’s Oort cloud, a population of small objects only loosely gravitationally bound to our Sun in a gigantic shell extending to about a third of the distance to the nearest star. Some of the objects in our Oort cloud eventually make it back into our solar system as long period comets while others may have slipped past the influence of the Sun’s gravity to become interstellar travelers themselves.

More interstellar visitors expected

The research team expects that ʻOumuamua is just the first of many interstellar visitors discovered passing through our solar system, and they are collectively looking forward to data from the Large Synoptic Survey Telescope (LSST) that is scheduled to be operational in 2022. The LSST, located in Chile, may detect one interstellar object every year and allow astronomers to study the properties of objects from many other solar systems.

While ISSI team members hope that LSST will detect more interstellar objects, they think it is unlikely that astronomers will ever detect an alien spacecraft passing through our solar system and they are convinced that ʻOumuamua was a unique and extremely interesting but completely natural object.

For the first time, astronomers at the University of �鶹��ý have demonstrated that the UH and survey telescopes can provide sufficient warning to move people away from the impact site of an incoming asteroid. The telescopes detected a small asteroid prior to its entering the Earth’s atmosphere near Puerto Rico on the morning of June 22, 2019.

The 4-meter diameter asteroid, which is about the size of a car and named 2019 MO, was observed four times in a span of 30 minutes by the ATLAS facility on Mauna Loa on �鶹��ý Island, at around midnight �鶹��ý time on the morning of Saturday, June 22. At that point, the asteroid was only 500,000 km from Earth—1.3 times the distance to the Moon. These initial observations were assessed by the NASA Jet Propulsion Laboratory’s (JPL) Scout impact analysis software, and the asteroid was given a modest impact rating of 2 (a rating of 4 is “likely”). However, JPL’s Davide Farnocchia noted a possible match with an atmospheric infrasound detection over Puerto Rico about 12 hours later, and he asked if the community could search for additional observations.

Luckily, the Pan-STARRS 2 (PS2) telescope on Haleakalā was operating at the same time, and two hours prior to the ATLAS observations had imaged the part of the sky where 2019 MO should have been seen. The asteroid was located on a part of the PS2 camera that is not fully operational, but PS2 scientists Robert Weryk and Mark Huber at the UH Institute for Astronomy and Marco Micheli at the European Space Agency were able to analyze these PS2 images and find the asteroid.

With these additional PS2 observations, the asteroid’s entry path prediction improved significantly, and new calculations by the Scout software increased the impact rating to 4 or “likely.” The improved orbit calculation also matched the infrasound detection with very high likelihood. The Nexrad weather radar in San Juan, Puerto Rico, also detected 2019 MO as it burnt up in the atmosphere, and pinpointed the entry location over the ocean, about 380 km south of San Juan, closely corresponding to the infrasound location.

Scanning the skies

ATLAS consists of two telescopes, 100 miles apart, with one on Mauna Loa, �鶹��ý Island, and one on Haleakalā, Maui. They automatically scan the whole sky every two nights, looking in all directions and see asteroids before they can hit the Earth. ATLAS currently discovers about 100 asteroids with diameters bigger than 30 meters every year.

Scientists estimate that asteroid 2019 MO was much smaller, only about 4 meters (13 feet) across. An asteroid that small would likely burn up entirely as it entered Earth’s atmosphere. The ATLAS telescopes can detect even such small objects about half a day before they arrive. It will find larger objects, like the one that exploded over Chelyabinsk, Russia, in 2013, a few days before they impact. That asteroid was about 20 meters across or the size of a house.

ATLAS and Pan-STARRS are funded by grants from the NASA Near-Earth Object Observations program.

More about UH ATLAS: UH ATLAS telescope pinpoints meteorite impact prediction, July 13, 2018; UH ATLAS telescope spots SpaceX Tesla Roadster in flight, February 9, 2018

More about Pan-STARRS at UH News.

Astronomers once thought asteroids were boring, wayward space rocks that simply orbit around the sun. Only in science fiction movies were they dramatic, changing objects.

New observations are turning science fiction into science fact, showing that asteroids are anything but dull. Asteroid Gault, discovered in 1998, has begun to slowly disintegrate. The crumbling was first detected earlier this year on January 5, by the University of �鶹��ý at Mānoa (IfA) (ATLAS) telescopes on Mauna Loa and Haleakalā. Later investigation proved there were no asteroid collisions.

“Each night the ATLAS survey scans the sky looking for hazardous near-Earth asteroids, and we also observe tens of thousands of known asteroids in the main asteroid belt,” said Larry Denneau, an ATLAS project scientist. “Our collaborator Ken Smith in Belfast, Ireland, found an unusual looking moving object, and he alerted us that it might be a new comet. Instead, it turned out to be an asteroid in the main belt that just developed a comet-like tail. These events are rare and mysterious, and we were lucky to detect the event right after its turn-on.”

Rare asteroid behavior

Gault is a well-known asteroid and the newly found tails are the first evidence of any misbehavior. These new observations suggest that asteroids are dynamic, active worlds that can ultimately disintegrate due to the long-term subtle effect of sunlight, which can slowly spin them up until they begin to shed material.

Astronomers estimate that this type of event is rare, occurring roughly once a year among the 800,000 known asteroids between Mars and Jupiter. That’s why only the latest astronomical surveys—like ATLAS—that map vast swaths of the sky nightly, can catch asteroids as they fall apart.

“Asteroids such as Gault cannot escape detection anymore,” noted Olivier Hainaut, a member of the observing team of the European Southern Observatory in Garching, Germany. “That means that all these asteroids that start misbehaving get caught.”

Observations find archival evidence

Once the new tail was discovered, Denneau and IfA colleague Robert Weryk looked back into archival data from ATLAS and the UH (Pan-STARRS) telescopes. The tail also turned up in data taken as far back as December 2018. In mid-January, a second shorter tail was detected by IfA astronomer Jan Kleyna using the Canada France �鶹��ý Telescope, as well as by other observers. An analysis of both tails suggests the two dust releases occurred last year around October 28 and December 30.

Tantalized by this new discovery, IfA astronomers Kleyna and Karen Meech, along with colleagues worldwide, began to observe Gault with telescopes around the world and in space. Spectacular images of asteroid 6478 Gault from NASA’s Hubble Space Telescope show two narrow, comet-like tails of debris streaming from the 2.5-mile-wide asteroid. The tails are telltale evidence that Gault is beginning to come apart by gently puffing off material in two separate episodes over the past several months.

Gault is only the second asteroid uncovered whose disintegration is decisively linked to a spin-up process, known as a YORP (Yarkovsky–O’Keefe–Radzievskii–Paddack) torque. When sunlight heats an asteroid, infrared radiation escaping from its warmed surface carries off momentum as well as heat. This creates a tiny force that can cause the asteroid to spin faster and faster. If this centrifugal force overcomes gravity, the surface becomes unstable, and landslides send dust and rubble drifting into space.