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For the Moon's current position and visibility, see the Planet Wheel.

The Moon

Moon of Earth

Proper Name	The Moon
Primary Planet	Earth
Orbital Period	27.4 days
Distance from Earth	Semi-Major Axis: 384,748 km Perigee: 363,625 km Apogee: 405,871 km
Eccentricity	0.0549 (mean)
Rotation Period	655 hours, 43 minutes
Magnitude	Full: -12.6, New: -2.5
Mean Diameter	3,476 km 2,159 miles
Notes	The single Moon of Earth is the fifth largest in the Solar System, comparable in size to Jupiter's moons of Io or Europa. It is tidally locked to Earth, so that from that planet, only one face remains permanently visible. This nearside face is marked by darker, relatively featureless regions known as maria or 'seas', features which are comparatively rare on the hidden farside of the Moon.

Key features on the visible face of the Moon.

The single large moon of the planet Earth. A cratered and barren body, its orbit is such that, within certain minor variations, it always shows the same face towards its mother planet.

The Moon, as seen from a nearby watery planet.

The first sliver of a New Moon, when the Moon begins to move away from the Sun in the sky, appears at intervals of about 29½ days. This regular event forms the basis of some of Earth's oldest calendars.

Earth's moon in comparison with its mother planet: the Moon's diameter is less than one third that of Earth.

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