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That weird ‘alien probe’ asteroid might not be an asteroid after all

Published Dec 18th, 2017 4:49PM EST
Image: ESO

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When astronomers first spotted the odd, cigar-shaped object later determined to be the asteroid Oumuamua a couple of months back, initial observations suggested it was a comet. Upon getting a better look at the object, and realizing it lacked the iconic comet “tail,” the scientists decided it must actually be an asteroid.

Now, after studying their data even more closely, it seems that at least some scientists are now second guessing their second guess, and that Oumuamua might actually be a comet after all.

The newest round of findings, which was published in the journal Nature Astronomy, was conducted by scientists with the Queen’s University Belfast. In the paper, lead author Alan Fitzsimmons discusses the difficult task of classifying the object due to it appearing different from both an asteroid and comet in various ways.

“Given that this object passed relatively close to our sun as it was traveling through our solar system, one would expect any ices on the surface to basically be heated and it should behave like a comet,” Fitzsimmons told “We should see gas streaming off the surface, we should see dust particles being ejected in the cometary atmosphere, perhaps even a tail.

Okay, so it’s an asteroid, right? Not so fast. “We didn’t see any signs of typical spectroscopic signatures that you would expect from the minerals on the surface of an asteroid we see in our solar system,” Fitzsimmons says.

So what is it? At the moment, the best guess science can offer is that it’s an interstellar comet which, due to its long trip through deep space, has been stripped of its surface ice. The resulting mass, which would be something like a hard, reddish carbon shell surrounding an icy body, may have gradually taken on a long, cylindrical appearance as it sped through space.