Last year, astronomers found the asteroid "Oumuamua," which traveled through our solar system upon arrival from another star. While a cigar-shaped asteroid passes through our solar system, scientists began theoretically to assume that asteroids could be from afar, and then stayed. Experts were still debating about the discovery, and Shmuel Bialy and Abraham Loeb, the latest theory at the Harvard Smithsonian Astrophysical Center, said that foreigners might have sent Oumumawa to survey other galaxies.
Professor Loeb told the Universe Today: "We explain that Oumoamua's excess acceleration away from the sun, as a result of the power that sunlight exerts on its surface.
"In order for this force to explain the measured excess acceleration, the object must be very thin so that the thickness is less than a millimeter, but tens of meters in size.
"It makes the object light on its surface and allows it to act as light sails.
"Its origins can either be natural (interstellar environments or proto-planetary disks) or artificial (like probes sent to an intelligence mission in the interior region of the solar system)."
However, the astronomer who discovered the asteroid Robert Weryk has criticized alien theory, calling it "wild" and "exotic".
Mr Weryk told the CBC at the drive in the afternoon: "I think it's the remainder of another solar system. It's just something that happened, came to us, and we really managed to operate the telescope tonight and look for it.
"It's theoretically predicted for decades, but we have never seen it. Unless we see another issue, we have a lot of questions that we simply can not answer."
Other astronomers also criticized Professor Loeb's theory.
Alens Fitssimmon, Queens University, Belfast astrophysicist recently said: "Like most scientists, I like to be convincing evidence of alien life, but that's not the case.
"It has already been shown that its observed characteristics correspond to a comet-shaped body that was pushed out of another star system.
"And some of the arguments in this study are based on figures with high uncertainty."
Katie Mack, an astrophysicist in North Carolina, was also involved with theory.
She wrote to Twitter: "What you understand is that scientists are completely happy to publish an outlandish idea if it has even the slightest chance of not being wrong.
"But while all other options are exhausted several times, even authors may not believe it."
It is believed that the unique cigar shaped space rock has been in the constellation among the stars for hundreds of millions of years, and this is the first foreign object that can be seen in our solar system.
"Oumuamua is about 400 meters long and dark red, and on October 19, 2017, a Pan-STARRS1 telescope was made in Hawaii, traveling about 95,000 kilometers an hour.