If you Google 'Oumuamua,' the official Wikipedia page will tell you that it's classed under the category 'comet,' but researchers, including from Harvard, will argue that maybe it could have been an alien probe instead.
What is 'Oumuamua'?
ʻOumuamua' which means "a messenger that reaches out from the distant past" in Hawaiian, is the first ever 'interstellar object' ever detected passing through the Solar System. It is formally designated 1I/2017 U1, and was discovered by Robert Weryk using the Pan-STARRS telescope at Haleakala Observatory, Hawaii, on 19 October 2017, 40 days after it passed from its closest point to the Sun.
An 'interstellar object' is a broad definition - it is anything other than a star or sub-star, that is located in interstellar space and is not bound by the gravitational pull to a star. It also classes objects that are on interstellar trajectory but are temporarily passing close to a star, such as certain asteroids and comets.
'Oumuamua' which looked like a cigar-shaped body floating in space was the first 'interstellar object' that was spotted.
Why could Oumuamua possibly be an alien probe?
When 'Oumuamua' was discovered, it showed no signs of a comet tail despite its close approach to the Sun, but has since undergone non-gravitational acceleration, potentially consistent with a push from solar radiation pressure. Oumuamua's system of origin and the amount of time it has spent traveling amongst the stars are also unknown. So the chances of Oumuamua being a comet are very slim.
If 'Oumuamua' is not a comet, then what else could it be?
Here's what Harvard researchers believe.
A new paper by researchers at the Harvard Smithsonian Center for Astrophysics raises the possibility that the elongated dark-red object, which is 10 times as long as it is wide and traveling at speeds of 196,000 mph, might have an "artificial origin."
"Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization," they wrote in the paper, which has been submitted to the Astrophysical Journal Letters.
The theory is based on the object's "excess acceleration," or its unexpected boost in speed as it traveled through and ultimately out of our solar system in January, this year.
"Considering an artificial origin, one possibility is that 'Oumuamua is a light sail, floating in interstellar space as a debris from an advanced technological equipment," wrote the paper's authors, Abraham Loeb, professor and chair of astronomy, and Shmuel Bialy, a postdoctoral scholar, at the Harvard Smithsonian Center for Astrophysics.
In the paper, the authors also reason how the object's high speed and unusual trajectory could be the result of it no-longer being operational. This could also explain the anomalies in this cigar-shaped objects travel path - its light-curve and low thermal emissions.
Spy craft or space junk?
Alan Jackson, fellow at the Centre for Planetary Sciences at the University of Toronto Scarborough, stated how the study was "distinctly lacking in evidence."
"The thing you have to understand is: scientists are perfectly happy to publish an outlandish idea if it has even the tiniest 'sliver' of a chance of not being wrong," astrophysicist and cosmologist Katherine Mack tweeted. "But until every other possibility has been exhausted dozen times over, even the authors probably don't believe it."
Is it likely to be an alien probe, though?
"But it's important to distinguish that the researchers who wrote the new paper have expertise in solar sails, so they're suggesting that 'Oumuamua could be like a solar sail," said Coryn Bailer-Jones of the Max Planck Institute for Astronomy. Bailer-Jones' paper on possible origin sites for 'Oumuamua was accepted by the Astrophysical Journal in September.
"Aliens would only come into all of this if you accept their assumption that 'Oumuamua is sail-like, and also assume nothing like that can be natural."
Katherine Mack also, does not completely rule out the possibility of it being an alien ship.
So if you see a headline saying that “scientists claim...” and it’s one paper and it’s an EXTREMELY BIG CLAIM, please keep in mind that the only thing you can conclude is that the authors of the paper (probably) didn’t see a reason the idea had to be 100% false.
— Katie Mack (@AstroKatie) November 6, 2018
Some of us are more conservative, of course. And it surely varies by field. But in my area (astrophysics/cosmology), there’s generally no downside to publishing something that’s (a) somehow interesting and (b) not completely ruled out, whether or not it ends up “the right answer”
— Katie Mack (@AstroKatie) November 6, 2018
So while 'Oumuamua' cannot definitely be ruled out as an alien object, it cannot also be called already recognized interplanetary body. What the object is, still remains the subject of speculation and debate, until a definite answer is found.
The more I read the news the more I hope Oumaouma is a spaceship that's gonna get me out of here.
— Matthew M. White (@matthewmwhite) December 13, 2017