- The point nearest to a star in the path of a body orbiting that star.More example sentences
- Also, relativistic advance of periastron has been studied and confirmed in certain binary stars with elliptical orbits.
mid 19th century: from peri- 'around' + Greek astron 'star', on the pattern of perigee and perihelion.
More definitions of periastronDefinition of periastron in:
- The US English dictionary