EarthMoonSun

The Earth–Moon–Sun relationship forms the primary gravitational and energetic system of the inner solar system. The Sun is a G-type star that provides the energy sustaining climates and drives the orbits of the Earth and Moon. The Earth orbits the Sun once per year, while the Moon orbits Earth roughly every month.

Distances and motions are organized around a common center of mass called the barycenter. The Earth–Moon system orbits the Sun with the same period as the Earth, but the Moon follows its own monthly orbit around Earth. The Moon’s average distance from Earth is about 384,000 kilometers, with an orbital period of about 27.3 days relative to the stars and about 29.5 days between successive new moons.

The Moon’s illumination varies as it orbits, producing the familiar phases from new moon to full moon. When the Sun, Moon, and Earth align, solar eclipses can occur; when the Earth lies between the Sun and Moon, lunar eclipses occur. These events are relatively rare from any single location due to orbital geometry.

Tides are a prominent effect of the Earth–Moon gravity. The Moon’s gravity creates ocean bulges that raise tides, while gravity interactions gradually adjust rotation and orbital periods, contributing to the Moon’s tidal locking—its same face consistently facing Earth.

The Sun’s energy balances Earth’s climate and weather and drives long-term planetary processes. The Sun contains most of the system’s mass and energy, shaping the dynamics of the Earth–Moon system and its place within the solar system. The Earth possesses an atmosphere and biosphere, the Moon is airless, and the Sun is a distant but dominant energy source.