Astronomical

google

ref

mid 16th century: via Latin from Greek astronomikos, from astronomia (see astronomy).

wiktionary

ref

Attested since at least 1550, from Middle French astronomique or directly from Latin astronomicus, from Ancient Greek ἀστρονομικός(astronomikós).

etymonline

ref

astronomical (adj.)

1550s, "pertaining to astronomy," from astronomy + -ical. Popular meaning "immense, concerning very large figures" (as sizes and distances in astronomy) is attested from 1899. Astronomical unit (abbreviation A.U.) "mean distance from the Earth to the Sun," used as a unit of measure of distance in space, is from 1909. Related: Astronomically.