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Distance from earth 384,400 km
Diameter 3,467 km, 0.272 times earth's diameter
Mass 0.0123 times earth's mass
Density 3.34
Gravity 0.17 times earth's gravity, escape velocity 2.4 km/s
Rotation 27.322 days
Orbit Eccentricity 0.05
Orbit Inclination 5.1 degrees
Axis Tilt 6.7 degrees
Sidereal Period 27.32166 Earth days
Synodic Period 29.53059 days

History: The moon is the second most noticable object in the sky next to the sun. Its name comes from the anglo-saxon word moneth, which later became the word used for month. The Greeks called the moon Selene, the Romans Luna.

Description: The moon is rather small, and therefore can hold very little of an atmosphere. Also, this allows the moon to be more heavily cratered than the planets, since it has no protective atmosphere. The features of the moon's geography are split up into three categories, seas, craters, and mountains. The seas, usually called maria, are the large, dark areasthat are relatively flat. It is believed that these seas were in fact lava plains billions of years ago when the moon was formed. The craters were almost all due to meteor impact. The moon also has mountain ranges, cliffs, vallies, and highland areas.

Observation: Contrary to popular belief, the best time to view the moon is not during a full moon. In fact, this is propably the worst time to observe the lunar surface. At this time, the suns light falls directly on the lunar surface, flattening its features. At times directly before and after full moon, the suns rays show the features in high relief. Large power binoculars or a small telescope is all that is reqired for observations of the moon. The best place to observe the lunar topography is along the terminator, the dividing line between the light and dark sides of the moon. This line moves slightly each night, and its motion can even be noticed over the course of a few hours, as the shadows of the moons surface change.