Skywatchers had high hopes that a comet called ATLAS would light up the night sky this spring, with forecasts suggesting it could become bright enough to see with the unaided eye.
Instead, the icy object crumbled to pieces — but it’s still putting on a spectacular show for scientists. Ye Quanzhi, an astronomer at the University of Maryland, snagged some time with NASA’s Hubble Space Telescope to take a look at Comet ATLAS on Monday (April 20) and caught a stunning image of its fragments that he shared on Twitter as a preview of his research.
“We have been following the break-up of ATLAS since it was first detected in early April, but with ground-based telescopes we couldn’t resolve most of the debris field,” Ye told Space.com in an email, adding that he was excited to see the new images. “With Hubble, we are finally able to resolve individual mini-comets.”
Ye hopes those mini-comets will help scientists understand what caused ATLAS to fall apart. In particular, astronomers rely on the distance between fragments to reconstruct events, since that distance increases as more time passes since a specific fracture.
Previous observations had identified four main fragments from Comet ATLAS. In the Hubble image, Ye said, he believes two of those fragments have broken down even more, yielding the two pairs of bright spots on the right, which represent the four largest fragments at the time.
The two clouds of brightness on the left may represent where older fragments have broken up into smaller pieces. Before beginning the observations, which lasted for one of Hubble’s orbits around Earth, Ye had hoped that Hubble would be able to spot more mini-comets in those regions, but it would appear those fragments had already disintegrated too far by the time the observations began.
Comet ATLAS is hardly the first icy space rock to break up within scientists’ view, but there are a few special conditions that make these new observations particularly exciting, Ye said. First, ATLAS happened to break up when it was quite close to Earth and quite bright, giving astronomers an especially clear view.
And ATLAS hails from the Oort Cloud, a distant sphere of icy rubble enveloping the solar system as much as 9.3 trillion miles (15 trillion kilometers) away from Earth. That vast distance makes it quite difficult for astronomers to study the Oort Cloud directly, but watching Comet ATLAS’s antics will help scientists develop new hypotheses about what’s happening out there.
ATLAS is only the second bright Oort cloud comet whose fragments Hubble has been able to observe in its 30 years of work, Ye said.