Interstellar Object 'Oumuamua Could Be Both an Asteroid and Comet

Monday, 18 December 2017 - 8:08PM
Space
Solar System
Monday, 18 December 2017 - 8:08PM
Interstellar Object 'Oumuamua Could Be Both an Asteroid and Comet
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M. Kornmesser/ESO
The speedy, cigar-shaped interstellar object 'Oumuamua may now be hurtling far beyond our reach, but it was fun having an outsider visit our solar system while it lasted.

'Oumuamua is the first recorded foreign material to travel into our solar system, as it took a trip around our sun before being fired off into the inky blackness of space (even if Elon Musk believes he could catch up to it if he really wanted to). The interstellar nomad has proven extremely interesting to astronomers, with plenty of new observations coming the longer we analyze data from 'Oumuamua's brief time with us.

One new insight suggests that 'Oumuamua may be some kind of special asteroid-comet hybrid, displaying both the signs of a rock and a chunk of ice at the same time.

While many believe that asteroids and comets are basically identical, the two terms refer to very different kinds of floating space debris - asteroids are hunks of rock that zip around the cosmos, while comets are mostly made of ice - hence the trail of vapor that follows in their wake.



At first, it was assumed that 'Oumuamua must be a comet. When our solar system was first created, the sun spat out huge chunks of ice which traveled far and wide at an incredible velocity; from this, astronomers assumed that other star systems must behave similarly, and figured that any visitor to our neck of the woods must have been one of these comets, shot out with great force from a distant star.

While this made sense at first, a lot of 'Oumuamua's movements didn't seem to match up with what would be expected from a comet. Quite aside from everything else, if a comet flew as close to our sun as 'Oumuamua did, there wouldn't be much left of it afterwards, as the heat would have caused it to melt. Thus, scientists reclassified 'Oumuamua as an asteroid.

Now, a new paper published in Nature suggests that 'Oumuamua is a comet, but one that's become encased in rock over the course of its travels. The paper posits that 'Oumuamua has picked up a layer of cosmic dust that protects its frozen heart, explaining why it behaves so strangely.

Certainly, different parts of the outer layer of 'Oumuamua appear to behave differently, which suggests that the rock has been picking up additional material as it's traveled. This coating isn't entirely dissimilar to matter on Earth, and under different circumstances, could even provide the material needed to kickstart life on a distant planet.

That said, 'Oumuamua almost certainly is not some kind of interstellar spaceship for a race of rocky aliens. Sadly, we'll have to keep waiting for someone out in the cosmos to return our calls, because 'Oumuamua isn't even aware that we exist.
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