Nicknamed "Oumuamua", the object has an exceptionally odd shape that distinguishes it from most asteroids and comets: It's a stadium-sized mass with a flat, elongated body that is reddish in color.
Oumuamua "might be a lightsail of artificial origin", the paper says, referring to an object created to use solar radiation for propulsion.
Experts have expressed scepticism about claims from two Harvard astronomers who say an interstellar object that passed through our solar system in late 2017 and early 2018 could have been part of an alien spacecraft.
It was moving at 59,030mph when it was first tracked by scientists.
Harvard researchers have now said it "may be a fully operational probe sent intentionally to Earth vicinity by an alien civilisation".More news: Iowa granny takes massive payout after winning US Powerball lottery
In a new scientific paper, Shmuel Bialy and Abraham Loeb of Harvard University in the USA will say cigar-shaped "Oumuamua" could be a spaceship.
Lightsails are a proposed method of spacecraft propulsion which uses radiation pressure exerted from sunlight or large mirrors. However, he adds that, if Oumuamua is indeed a lightsail, it may have run into our solar system "like a ship bumping into a buoy on the surface of the ocean".
"This would account for the various anomalies of 'Oumuamua, such as the unusual geometry inferred from its light-curve, its low thermal emission, suggesting high reflectivity, and its deviation from a Keplerian orbit without any sign of a cometary tail or spin-up torques".
The paper, written by Abraham Loeb, professor and chair of astronomy, and Shmuel Bialy, a postdoctoral scholar, at the Harvard Smithsonian Center for Astrophysics, points out that comparable light-sails already exist on earth.
"Not 'where is the lack of evidence so that I can fit in any hypothesis that I like?"More news: Rivers, Gordon leads Chargers past Seahawks 25-17
"It is going extremely fast and on such a trajectory that we can say with confidence that this object is on its way out of the solar system and not coming back", Mr Farnocchia said shortly after its discovery.
He raised questions in particular about the object's tumbling motion.
"Why send a spacecraft which is doing this?" he said. It's also possible Oumuamua was just created to wander through space, collecting information, and our solar system just happened to be in its way - its operators weren't necessarily looking to pry into the lives of humans.
When the object was first spotted scientists believed it might have been travelling through space for hundreds of millions of years. That means the object would be made of some thin material that could absorb radiation from the sun - either a naturally created material we've never seen before, or something made by aliens.More news: Rihanna Slams Donald Trump For Playing Her Music