Intrinsic and
Orbital Properties

The mass of the Moon is about 1/80 that of the Earth, and its diameter is about 1/4 that of the Earth. The orbit of the Moon is very nearly circular (eccentricity ~ 0.05) with a mean separation from the Earth of about 384,000 km, which is about 60 Earth radii. The plane of the orbit is tilted about 5 degrees with respect to the ecliptic plane. The Apollo missions to the Moon left devices that can reflect laser light sent to the moon from the Earth. By timing the roundtrip of such light, it is possible to determine the distance to the Moon at any particular time with an uncertainty of only a few centimeters (!).

Since the synodic rotational period of the Moon is 29.5 days, Lunar day and Lunar night are each about 15 Earth days long. During the Lunar night the temperature drops to around -113 degrees Celsius, while during the Lunar day the temperature reaches 100 degrees Celsius. The temperature changes are very rapid since there is no atmosphere or surface water to store heat.