A top Harvard astronomer has claimed that earth, or at least our solar system, may have already been visited by aliens.

Avi Leob, a Professor of Science at Harvard University, said that there is evidence to support his claims that an extraterrestrial object that passed by our solar system in 2017 may have been constructed by alien technology.

Leob, the author of a new book called "Extraterrestrial: The First Sign of Intelligent Life Beyond Earth" has been trying to convince his peers in the scientific community to consider the possibility that aliens may have already visited our solar system.

In his book, Leob claims that the highly unusual characteristics of the object that passed through the solar system - dubbed Oumuamua, which is "scout" in Hawaiian is a valid argument for his hypothesis.

Leob's credentials, including numerous awards and published papers, has carried some weight to his claims. His work in astronomy and cosmology also makes him difficult to dismiss outright.

Leob repeatedly mentioned in his book that scientists should be modest and work together to explore anomalies and unexplained phenomena. This includes a closer look at the alien object that passed through our solar system.

"Thinking that we are unique and special and privileged is arrogant. The correct approach is to be modest and say: 'We're nothing special, there are lots of other cultures out there, and we just need to find them'," Leob said.

In 2017, astronomers had detected an object moving quickly through our solar system. Scientists agreed that its trajectory and speed meant that it had come from another star. The object was the first recorded interstellar visitor since humans began to explore space.

Scientists observed that the object was not moving in accordance with the laws of physics, seemingly moving through the influence of a mysterious force. The object, which was described to be long and thin like a cigar, deviated from its expected trajectory after its slingshot around the Sun.

The general scientific community dismissed the anomaly and most had come up with novel theories to explain away the discrepancies. This included theories on why the object was not expelling any gas or debris or why it was unusually luminous.

"These ideas that came to explain specific properties of 'Oumuamua always involves something that we have never seen before. If that's the direction we are taking, then why not contemplate an artificial origin?," Leob said.