The average motion of any body within a given period. The mean motion of a planet is based on the presumption that it moves in a circle at a uniform rate about the Sun. Actually the planets move in elliptical orbits, in portions of which this motion is accelerated and retarded in ratio to their distance from the gravitational center. The mean daily motions of the planets are:
Pluto |
0° 0' 14" |
Jupiter |
0° 4'59" |
Neptune |
0° 0' 24" |
Mars |
0° 31' 0" |
Uranus |
0° 0' 42" |
Venus |
1° 36' 0" |
Saturn |
0° 2' 1" |
Mercury |
4° 6' 0" |
The Moon |
(around the Earth) |
13° 10'35" |
|
The Earth |
(around the Sun) |
0° 59' 8" |
The Heliocentric mean motions of the planets differ from their geocentric motions.
