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:

Apsidal precession — the Moon’s orbit rotates once every 8.85 years. [Image: Wikimedia]

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.


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:

The moon’s orbit around Earth is very nearly circular, but not a perfect circle. Sometimes the moon is closer to Earth than at other times. That’s the case with the Hunter’s Moon of 2015. [Diagram by Brian Koberlein. Image and text: earthsky.org]
  • apogee – Merriam Webster
  • apogee – Oxford Dictionaries
  • apogee – Cosmos, Swinburne University of Technology
Featured Image



Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out / Change )

Twitter picture

You are commenting using your Twitter account. Log Out / Change )

Facebook photo

You are commenting using your Facebook account. Log Out / Change )

Google+ photo

You are commenting using your Google+ account. Log Out / Change )

Connecting to %s