Interstellar object 'Oumuamua could be a 'monstrous' corpse of comet dust
Oumuamua, the first known visitor from beyond our Solar System, is long gone, but it's still leaving scientists guessing. A new explanation proposes that the strange object was a "monstrous fluffy dust aggregate" produced by a busted-up comet.
That's the explanation laid out by Zdenek Sekanina, an astronomer at NASA's Jet Propulsion Laboratory. The explanation draws on observations of comets breaking apart as they get closer to the Sun.
'Oumuamua is the interstellar object that astronomers detected whizzing through our Solar System in October 2017. It was the first interstellar object scientists ever spotted, although they expect thousands more have gone unnoticed. Ever since 'Oumuamua's appearance scientists have debated what the object is: asteroid or comet, ripped-up planetesimal or, the least likely, an alien probe.
The research adds another loop to the already-knotty issue by suggesting that the object changed during its brief time in our Solar System: while the object appeared reddish, long and thin during its exit, it may have started out with different properties.
'Oumuamua has been compared to other faint but more mundane comets that astronomers have observed. Typically, when these faint comets come within a quarter of Earth's distance from the Sun they don't survive the visit, experiencing an outburst that triggers their disintegration.
The research considers comet C/2017 S3 (PANSTARRS), which crept in from the Oort Cloud. This comet experienced two violent outbursts before finally falling apart – it’s thought C/2017 S3's remains had become "a monstrous, extremely fluffy aggregate of loosely bound dust grains" before it made its closest approach to the Sun.