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Hubble Telescope Watches the Rare Disintegration of a Comet

posted by Jason Kottke   Apr 29, 2020

Last month, I told you about Comet ATLAS, which at that time looked capable of putting on a real show in the night sky.

Except, since its discovery, the comet has been brightening at an almost unprecedented speed. As of March 17, ATLAS was already magnitude +8.5, over 600 times brighter than forecast. As a result, great expectations are buzzing for this icy lump of cosmic detritus, with hopes it could become a stupendously bright object by the end of May.

It turns out the increase in brightness was fleeting — and possibly due to the comet breaking apart. In the past week, the Hubble Space Telescope has gotten two good looks at the disintegrating comet, identifying that the main mass has broken into about 30 fragments.

Comet Atlas Hubble

Comet Atlas Hubble

“This is really exciting — both because such events are super cool to watch and because they do not happen very often. Most comets that fragment are too dim to see. Events at such scale only happen once or twice a decade,” said the leader of a second Hubble observing team, Quanzhi Ye, of the University of Maryland, College Park.

The results are evidence that comet fragmentation is actually fairly common, say researchers. It might even be the dominant mechanism by which the solid, icy nuclei of comets die. Because this happens quickly and unpredictably, astronomers remain largely uncertain about the cause of fragmentation. Hubble’s crisp images may yield new clues to the breakup. Hubble distinguishes pieces as small as the size of a house. Before the breakup, the entire nucleus may have been no more than the length of two football fields.