What does pericentre mean?
A pericentre is the point in an elliptical orbit at which a body is closest to the mass around which it travels. For a satellite orbiting a planet, this is the point of closest approach to the planet's centre; for a planet orbiting the Sun, it is the point at which the planet lies nearest the Sun. The word is especially familiar in discussions of the Moon, whose orbit brings it close to Earth at every pericentre and farther away at the opposite, or apocentric, point. In British English the usual spelling is pericentre, while US usage often prefers pericenter. Although the concept applies to any elliptical orbit under gravity, the term is primarily used in astronomy. Its usefulness lies in identifying the precise stage of an orbit at which distance from the attracting body is minimal, allowing orbital geometry, timing, and gravitational conditions to be described accurately.
nounThe point in an elliptical orbit at which a body is closest to the centre of mass around which it is moving.
- The point in an elliptical orbit at which a body is nearest the central body or other mass attracting it.
"The Moon reaches its pericentre each month when it is closest to Earth."
"Earth's orbit brings it to its pericentre in early January, when it is closest to the Sun."
"The satellite's orbital calculations account for the small variations in gravity encountered near pericentre."
The standard British plural is “pericentres”; US spelling commonly gives “pericenters.”
"The observations revealed changes in the orbit's pericentres over time."
A lunar pericentre is the Moon's closest approach to Earth—a brief monthly rendezvous with our home planet.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does pericentre come from?
The word was formed in astronomical usage from the Greek combining form peri-, meaning “around,” and kentron, meaning “centre.” These elements express the idea of a point surrounding or nearest the centre of an orbit. The modern astronomical term belongs to a family of Greek-based expressions that includes perigee, the point of an orbit closest to Earth, and perihelion, the point of a planetary orbit closest to the Sun.
Related word forms
How pericentre is actually used
In British English, “pericentre” is standard; US English more commonly uses the spelling “pericenter.” The term is chiefly astronomical and is usually used for an orbiting body and the central mass or system it orbits.
Easily confused with pericentre
Pericenter is the US spelling of the same word used in British English.