The paper was written by Professor Abraham Loeb, the director at Harvard's Center for Astrophysics's Institute for Theory and Computation, and Shmuel Bialy, a postdoctoral researcher. While there's a possibility that the object is merely an abnormally thin, extremely large naturally-occurring piece of interstellar rock - it didn't emit any radio signals detectable by human instruments - they speculate that it could be a defunct light-sail, space detritus fallen from a long-gone ship. According to the researchers, the object's unusual, elongated shape and unexpected trajectory ruled out conventional possibilities, including an asteroid.
The researchers noted in a pre-print of the article that it was an "exotic scenario", but that "Oumuamua may be a fully operational probe sent intentionally to Earth vicinity by an alien civilization".
Asked if he believed the hypothesis he put forward, Bialy told AFP: "I wouldn't say I "believe" it is sent by aliens, as I am a scientist and not a believer, I rely on evidence to put forward possible physical explanation for observed phenomena". It was dubbed 'Oumuamua, which means "scout" in Hawaiian.
It is ten-times as long as it is wide and travels at speeds of 196,000 miles per hour.
This would explain various anomalies "Oumuamua" such as the unusual geometry of its light curve, its low heat emission, suggesting high reflectivity and its deviation from the Keplerian orbit without any signs of a cometary tail or spin-torque.
Since its discovery, scientists have found themselves puzzled due to the unusual features of the interstellar object. Instead of the normal mechanic used by comets to accelerate (called "outgassing"), the authors suggest solar radiation pressure could explain 'Oumuamua's behavior.More news: Queen invites Meghan Markle's mother to spend Christmas with the royal family
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Scientists have been puzzling over "Oumuamua" ever since the mysterious object was seen tumbling past the sun in late 2017.
The truth may be hard to establish, as Oumuamua has left the solar system and is no longer visible even with telescopes.
The change in course and speed was so pronounced they concluded it "might be a lightsail of artificial origin".
So far, there is no obvious origin for 'Oumuamua. Not all shells are the same, and similarly only a fraction of the interstellar objects might be technological debris of alien civilizations.
"A survey for lightsails as technosignatures [scientific evidence of past or present technology] in the solar system is warranted, irrespective of whether Oumuamua is one of them", the paper said.
The only other explanation that comes to mind is the extra force exerted on Oumuamua by sunlight.