In ufology, the Extraterrestrial Hypothesis ( ETH ) theorizes that UFOs come from outer space and probably originate on another planet in another star system. Although more exotic locations such as alternate universes are also technically extraterrestrial, they are usually referred to as something other than the ETH. It is doubtful that the smaller UFOs that have been reported made an interstellar journey on their own. Instead most ufologists agree that they are probably shuttles or reconnaissance craft that have been dispatched from a mother ship near the Earth. Alien beings from space or another planet are often referred to as extraterrestrials or ETs.