Ancient astronaut theories are various proposals that the Earth had, before first human record, been visited by intelligent extraterrestrial beings, and that such contact is linked to either the origins or development of human cultures, technologies and/or religions.
Indeed, some of these theories suggests that gods from most — if not all — religions are actually extraterrestrial beings, and their technologies were mistaken for divine entities by early man. While no peer-reviewed scientific journal validates such claims, these theories have been popularized, particularly in the latter half of the 20th century, by writers Erich von Däniken, Zecharia Sitchin and others.
Ancient astronaut theories also may include the idea that civilization may have evolved on earth twice, and that the visitation of ancient astronauts may reflect the return of descendants of ancient humans whose population was separated from earthbound humans.
Proponents of ancient astronaut theories point to what they perceive as gaps in historical and archaeological records and also what they see as an absence of definitive explanations in certain contexts from the archaeological sciences.
Advocates of these theories put forward as evidence their interpretations of various archaeological artifacts, which they deem to have been anachronistic or beyond the presumed technical capabilities of the historical cultures they are associated with (see “OOPArt”). Another common theme relies upon the interpretation of depictions in certain ancient artworks as being representations of actual extraterrestrial visitors as realised by the contacted cultures.
Critics maintain, however, that any gaps in contemporary knowledge of the past do not demonstrate that such speculative ideas are a necessary, or even plausible, conclusion to draw from the available data. A number of ancient astronaut claims are made in direct opposition to the consensus scientific interpretation of evidence and to legitimate scientific explanations. The scientific community remains generally skeptical, and the dominant view is that there is no actual evidence to support ancient astronaut and paleocontact theories.
Ancient astronaut theories may be considered a subset of paleocontact theory, a hypothesis that intelligent extraterrestrials have visited Earth. Carl Sagan, I.S. Shklovskii and Hermann Oberth are three notable scientists who have seriously considered this possibility.
