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This article is about the astronomical term. In architecture, apsis is also the plural of apse.
Apogee is also the name of a major video game publisher.
In astronomy, an apsis is the point of greatest or least
distance of the elliptical orbit of a
celestial body from a center of attraction. The point of closest approach is called the periapsis and the point
of farthest approach is the apoapsis.
According to Kepler's laws of
planetary motion, as a body approaches the periapsis it will increase in velocity and as a body approaches the apoapsis it will decrease in velocity.
When the body the orbit is around is known, more specific names are often used.
| Body being orbited |
Closest approach |
Farthest approach |
| Earth |
perigee |
apogee |
| The Sun |
perihelion |
aphelion |
| A star |
periastron |
apastron or apoastron |
| The Moon |
perilune |
apolune |
| Jupiter |
perijove |
apojove |
| A black hole |
perimelasma |
apomelasma |
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