Mid 19th century; earliest use found in John Pringle Nichol (1804–1859), astronomer and political economist. From peri- + ancient Greek ἀστήρ star, after perigee, perihelion, etc. Compare French périastre.
Definition of periaster in US English:
periaster
nounˌpɛrɪˈastə
Astronomy rare
Periastron.
Origin
Mid 19th century; earliest use found in John Pringle Nichol (1804–1859), astronomer and political economist. From peri- + ancient Greek ἀστήρ star, after perigee, perihelion, etc. Compare French périastre.