[astr-] or astro- comb form [ME astro-, fr. OF, fr. L astr-, astro-, fr. Gk, fr. astron--more at star]: star: heavens: outer space: astronomical "astrophysics"
ASTR-
Meaning of ASTR- in English
Merriam-Webster English vocab. Английский словарь Merriam Webster. 2012