Orbit of the Moon and Lunar theory

The Moon makes a complete orbit around the Earth with respect to the fixed stars about once every 27.3 days^{[nb 5]} (its sidereal period). However, since the Earth is moving in its orbit about the Sun at the same time, it takes slightly longer for the Moon to show the same phase to Earth, which is about 29.5 days^{[nb 6]} (its synodic period).^[12] Unlike most satellites of other planets, the Moon

The Earth-Moon system, not drawn to scale.^[77] Both individual radii and the barycenter radii are given

orbits near the ecliptic and not the Earth's equatorial plane.

There are several known near-Earth asteroids that have unusual Earth-associated horseshoe orbits: 3753 Cruithne, 54509 YORP, (85770) 1998 UP1 and 2002 AA29.^[79] They are co-orbital with the Earth, so that their orbits bring them close to Earth for periods of time but then alter in the long term, and they are not natural satellites of Earth.^[80]