periapsis

American  

[per-ee-ap-sis] / ˌpɛr iˈæp sɪs /

noun

plural

periapses, periapsides

1. Astronomy. (in technical usage) the preferred term for pericenter.

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periapsis Scientific  

/ pĕr′ē-ăp′sĭs /

plural

periapsides

1. The point at which an orbiting object is closest to the center of mass of the body it is orbiting. This point is sometimes given a name that is specific to the body being orbited. For example, the periapsis of an object orbiting Earth is its perigee (from gaia, the Greek word for Earth), and the periapsis of an object orbiting the Sun is its perihelion (from hēlios, the Greek word for Sun). According to Kepler's laws of planetary motion, an object is at its greatest velocity at the periapsis.

2. Compare apoapsis

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Example Sentences

Each flight with Jebediah or Valentina at the helm started out with such promise: Preflights checked, angles maintained, periapsis achieved and stable orbit reached.

From Slate • Jul. 20, 2019

In an elliptical orbit, the periapsis is the point at which the two objects are closest, and the apoapsis is the point at which they are farthest apart.

From Textbooks • Feb. 13, 2015

Generally, the velocity of the orbiting body tends to increase as it approaches the periapsis and decrease as it approaches the apoapsis.

From Textbooks • Feb. 13, 2015