NASA Scientist Claims Earth May Have Been Visited by Extraterrestrials

Video: Strange object found in the Baltic Sea

A UFO-shaped gate is seen at the entrance to Alto Paraiso town, Goias State, in Brazil. EVARISTO SA/AFP/Getty Images

A NASA scientist has claimed that Earth may have been once visited—or is being visited—by extraterrestrials, but we may not have realized it.

Silvano P. Colombano, who works at NASA Ames Research Center and is also a professor, theorizes that intelligent life may not be carbon-based or what we’re used to.