A physicist has weighed in on the mystery surrounding the interstellar object 'Oumuamua,' which flew past Earth back in 2017 at an unusually high speed.
Harvard professor Avi Loeb remarked during an interview with Salon that it's possible the fast, cigar-shaped object was an interstellar spacecraft.
"At first, astronomers assumed it must be a comet, because these are the objects that are most loosely bound to stars," Loeb said. "The problem with that was there was no cometary tail."
Loeb wrote a book on the topic, titled: "Extraterrestrial: The First Sign of Intelligent Life Beyond Earth." The book is set to be released next week.
"Some people say, 'OK it's not a comet, maybe it's just a rock.' But the problem is, about half a year later, it was reported that there was an excess push in addition to the force of gravity acting on it by the sun," he continued. "It exhibited some additional force. Usually that force comes from the rocket effect of the cometary tail, but there was no cometary tail. So the question was, what produces this excess push?"
Loeb told the website there was another object discovered that exhibited an excess push called 2020-SO, which he said ended up being a rocket booster from a failed mission of lunar lander, Surveyor II that was launched in 1966. He said because that object was artificially made and had no cometary trail, it "provides evidence" that we can tell the difference between a rock and an object -- like the rocket booster -- that is pushed by sunlight.
"To me, it demonstrated the case that perhaps 'Oumuamua was artificial, definitely not made by us because it's been only a few months close to us. We couldn't even chase it with our best rockets," he told Salon.
Loeb added that it was on the "shinier end of all the objects we have seen from the solar system."
In November 2018, a study published by Loeb and others at the Harvard Smithsonian Center for Astrophysics suggested 'Oumuamua could be "a lightsail of artificial origin" sent from another civilization. However, the researcher who discovered 'Oumuamua, Canadian physicist and astronomer Robert Weryk, said the idea it was from another civilization was just "wild speculation."
'Oumuamua, which means "pathfinder" or "scout" in Hawaiian, was first classified as an asteroid when it was spotted in 2017 traveling at 196,000 mph. However, it had recently been found more akin to a comet.
NASA confirmed that it is the "first object ever seen in our solar system that is known to have originated elsewhere."
Fox News' Chris Ciaccia contributed to this report