Definitions

1. noun

The point in an elliptical orbit where a celestial body is closest to the star it orbits around.

“The periastron of the planet occurs every 18 months, causing the planet’s surface temperature to fluctuate significantly.”

2. noun

A point in the orbit of a binary star system where one star is at its closest to the other.

“Astronomers have tracked the periastron of the binary star system, providing valuable insights into its behavior.”