planetarian
/ˌplanɪˈtɛːrɪən/adjective
Of or relating to a planet or planets; planetary. Now rare.
noun
An inhabitant of a planet (usually, other than the earth).
Origin
Mid 17th century; earliest use found in John Gaule (1603/4–1687), Church of England clergyman and author. From post-classical Latin planetarius planetary + -an.