1550s, 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 Earth to Sun," used as a unit of measure of distance in space, is from 1909. Related: Astronomically.
1. Houses in the village are selling for astronomical prices.
2. the astronomical costs of land for building
3. He was an expert on ancient Chinese astronomical literature.
4. Light - year is an astronomical unit.
5. The naming of stars is at the discretion of the International Astronomical Union.