Harvard professor explains we may have ALREADY been visited by aliens for THIS reason ALIENS may have already visited Earth without us even noticing, according to a top Harvard professor. Share: Facebook Twitter Google+ Stumble Digg Email ThisBlogThis!Share to XShare to Facebook Related Posts:Telescope to Seek Earthlike Planet in Alpha Centauri SystemQ&A: The Trees of New York CityDogs Can Train Us to Have a Better Sense of SmellClimate Change Blamed for Half of Increased Forest Fire DangerScienceTake: Jaws: The Tale of the Fearsome Stag BeetleBeetle Battle