What branch was Carl Sagan in?

Carl Sagan was primarily associated with the field of astronomy and astrophysics. He made significant contributions to planetary science and was a prominent advocate for the search for extraterrestrial life. Sagan was also involved in various scientific outreach efforts, popularizing science through his books and the famous television series "Cosmos." Additionally, he worked as a professor and researcher, contributing to our understanding of planetary atmospheres and the potential for life beyond Earth.