Astronaut

An astronaut (from the Ancient Greek ἄστρον (astron), meaning 'star', and ναύτης (nautes), meaning 'sailor') is a person trained, equipped, and deployed by a human spaceflight program to serve as a commander or crew member of a spacecraft. Although generally reserved for professional space travelers, the term is sometimes applied to anyone who travels into space, including scientists, politicians, journalists, and space tourists. In the United States, it is a designated term used by three agencies: NASA, the FAA, and the military. The term is also used for people who are trained to fly in a spacecraft after passing certain training courses, regardless of their experience of space travel.

"Astronaut" technically applies to all human space travelers regardless of nationality. However, astronauts fielded by Russia or the Soviet Union are typically known instead as cosmonauts (from the Russian "kosmos" (космос), meaning "space", also borrowed from Greek κόσμος). Comparatively recent successes of the China Manned Space Program have led to the rise of the informal term taikonaut (from the Mandarin "tàikōng" (太空), meaning "space"); Chinese official media refers to its astronauts and their foreign counterparts as hángtiānyuán (航天员, meaning "celestial navigator" or literally "heaven-sailing staff"). The Canadian Space Agency, European Space Agency, and JAXA refer to their crew as astronauts regardless of launch vehicle; historically other nationalities launched by the Soviet Interkosmos adopted the cosmonaut term.

As of April 2026, 781 humans have flown in space, many of these to space stations. Over 290 individuals have visited the International Space Station; 105 individuals visited the Mir station.