Mondbahn

Mondbahn is the orbital path of the Moon around the Earth. The Moon completes a sidereal orbit in about 27.3 days and a synodic cycle of about 29.53 days with respect to the Sun. Its average distance from Earth is approximately 384,400 kilometers, while the orbit is slightly elliptical with an eccentricity around 0.0549.

The Moon’s orbit is inclined about 5.145 degrees to the ecliptic plane. The line of nodes where the Moon’s orbit crosses the ecliptic regresses over an 18.6-year cycle due to solar perturbations. The distance varies between perigee near 363,300 kilometers and apogee near 405,500 kilometers. The orbit also undergoes slow apsidal and nodal precession, and its orientation is continually altered by gravitational influences from the Earth, the Sun, and other planets.

Because the Moon is tidally locked to Earth, the same hemisphere generally faces our planet. The combination of orbital eccentricity and inclination produces librations that allow observers to see about 59 percent of the lunar surface over time. The synodic cycle governs the lunar phases and is a key factor in the timing of solar and lunar eclipses.

Modern studies of Mondbahn rely on precise measurements such as lunar laser ranging, radar tracking, and spacecraft tracking to produce accurate ephemerides. These data support navigation and mission planning for lunar exploration, improve models of tidal evolution and rotational dynamics, and enhance understanding of the Earth–Moon system.