Orbit of the Moon

Orbit of the Moon

Diagram of the Moon's orbit with respect to the Earth. While angles and relative sizes are to scale, distances are not.
Semi-major axis	384,748 km (239,071 mi)
Mean distance	385,000 km (239,000 mi)
Inverse sine parallax	384,400 km (238,900 mi)
Perigee	363,228.9 km (225,700.0 mi), avg. (356400–370400 km)
Apogee	405,400 km (251,900 mi), avg. (404000–406700 km)
Mean eccentricity	0.0549006 (0.026–0.077)
Mean obliquity	6.687°
Mean inclination
of orbit to ecliptic	5.15° (4.99–5.30)
of lunar equator to ecliptic	1.543°
Period of
orbit around Earth (sidereal)	27.322 days
orbit around Earth (synodic)	29.530 days
precession of nodes	18.5996 years
precession of line of apsides	8.8504 years

The Moon takes 27.3 days (3.9 weeks) to orbit around the Earth. One side of the Moon faces the Earth at all times, so the moon is tidally locked to Earth.

The phases of the Moon come from the position of the Moon relative to the Earth and Sun. If the Moon and Sun are on opposite sides of the Earth, there is a full moon. If they are on the same side of Earth, there is a new moon.

The Moon makes one circle around Earth, called the sidereal month, in 27.3 days. But in this time, the Earth continues to move forward, so the Moon will be in a different place relative to the Sun, and the phase of the Moon will be different. To reach the same phase, the Moon must travel a bit farther. The time for the Moon to reach the same phase, called the synodic month, is 29.5 days.