Our solar system’s second known interstellar visitor doesn’t seem to be in one piece anymore.
Photos of the interstellar Comet Borisov taken by NASA’s Hubble Space Telescope on March 28 and March 30 show an elongated nucleus that appears to have two distinct components, astronomers announced in a note Thursday (April 2). That’s a very different situation than the one Hubble observed on March 23, when the nucleus was a single entity.
These two pieces are about equally bright, but that doesn’t mean they’re of equivalent size, said UCLA astronomer David Jewitt, who led the new observations
“Actually, it turns out almost never to be that case,” Jewitt told Space.com, referring to similar observations of native-born comets.
“Usually, the main nucleus drops off a piece, and the piece is small compared to the main nucleus — it contains a tiny fraction of the total mass,” he said. “But, because it was just plucked out of the nucleus, it’s pretty icy. And the ice fizzes and sublimates like crazy, making it a good producer of dust.”