Avi Loeb, the head of Harvard University's Department of Astronomy is convinced that aliens have already visited our solar system.
Loeb believes that a relatively small object – roughly the size of a football field – that drifted into the solar system's orbital plane in 2017 was not an ordinary comet as other scientists concluded. The Harvard professor said that was the easy, even lazy, explanation.
"What would happen if a caveman saw a cellphone?" Loeb said in an upcoming book. "He's seen rocks all his life, and he would have thought it was just a shiny rock."
Loeb concluded that what astronomers observed was alien trash. Specifically, he believes it was discarded technology from an alien civilization.
Loeb said the object's varying brightness, cigar-shape (which Loeb argues was more like a sail), and its irregular movement away from the sun – indicating it was being pushed by a force beyond just the sun's gravity – convinced him this was something extra-terrestrial.
"The only way to look for [alien civilizations] is to look for their trash, like investigative journalists who look through celebrities' trash," Loeb said.
Though the International Space Science Institute said there was "no compelling evidence" for any kind of alien explanation, Loeb says they are willfully ignoring the evidence.
"Some people do not want to discuss the possibility that there are other civilizations out there," the Harvard professor said. "They believe we are special and unique. I think it's a prejudice that should be abandoned."