Ancient Aliens is an American television series produced by Prometheus Entertainment that explores the pseudoscientific hypothesis of ancient astronauts in a non-critical, documentary format. Episodes also explore related pseudoscientific and pseudohistoric topics, such as: Atlantis and other lost ancient civilizations, extraterrestrial contact and ufology, and popular conspiracy theories. The series, which has aired on History since 2010, has been a target for criticism of History's channel drift, as well as criticism for promoting unorthodox or unproven hypotheses as fact. According to Smithsonian, episodes of the series overwhelm the viewer with "fictions and distortions" by using a Gish gallop.