UAP meaning in Space Science ?

An unidentified flying object (UFO) is any perceived aerial phenomenon that cannot immediately be identified or explained. Most UFOs are identified or investigated as conventional objects or phenomena. The phrase was coined as an acronym by Project Blue Book head Edward J. Ruppelt, but today UFO is widely used as a stand-in for extraterrestrial spacecraft-aircraft that people claim to have observed. Many UFOs are described as being flying saucers, as is shown in the accompanying image.

Studies and investigations into UFO reports have been conducted by governments, other organisations, and private individuals. In the United States, studies began in the late 1940s and have included Project Grudge, Project Sign and Project Blue Book. The latter ended in 1969–1970 after the Condon Committee concluded that the subject failed to merit further study.

Unidentified lights and flying objects have been reported for much of human history. Skeptics including scientists, and organizations such as the Committee for Skeptical Inquiry, state that UFOs are conventional objects or phenomena, while "Ufologists" favour unconventional hypotheses. UFOs are a worldwide cultural phenomenon, appearing in fictional movies, television and other media. UFO reports continue to appear in news media.