apogee

The highest point in the development of something — a climax or culmination; the point in the orbit of the moon or a satellite at which it is furthest from the earth — the opposite of perigee.

—Oxford Dictionary

[Late 16th century: from French apogée or modern Latin apogaeum, from Greek apogaion or apogeios (diastēma), ‘(distance) away from earth’, — apo from + (gaia) earth]

First Known Use: 1594

This exaggerated (not to scale) schematic representation below shows the variation of the moon’s distance from the earth through its elliptical orbit:

For the Moon or an artificial satellite moving around the Earth in an elliptical orbit, the distance between the object and the Earth changes throughout the orbit. The point of maximum separation from the Earth is known as the apogee (from the Greek apo = away from). At this point in the orbit, the object is moving at its slowest speed (Kepler’s Second Law). The apogee refers specifically to orbits around the Earth (cf. apoapsis, the equivalent position of a general orbit). The point of closest approach between the Earth and a celestial object orbiting it is the perigee.

Cosmos

In reality, the moon’s orbit around the earth is not such a pronounced ellipse as suggested by the image above, but rather traces a much more compact ellipse (image below). Nonetheless, the principle of apogee and perigee hold true:

References
  • apogee – Merriam Webster
  • apogee – Oxford Dictionaries
  • apogee – Cosmos, Swinburne University of Technology
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