The Moon

Abstract

The moon, at a mean distance of 384,404 km (240, 252 miles) from Earth, is the closest and the most thoroughly studied celestial body. It is the only body outside Earth that we have tread on, and will probably remain so for many years. As the moon moves in its elliptical orbit around us, its distance from the center of Earth varies from a minimum of 356,400 km to a maximum of 406,700 km. As seen from Earth this orbital motion of the moon makes it appear to move about 13° eastward (opposite to its apparent westward rising and setting motion, which is due to the rotation of Earth) each day. Owing to this apparent eastward motion, which, as noted, stems from the actual revolution of the moon around Earth, the moon rises about 52 minutes later each day for any observer on Earth.

To behold the wandering moon,

Riding near her highest noon,

Like one that had been led astray

Through the heav’n’s wide pathless way

And oft, as if her head she bowed,

Stooping through a fleecy cloud.

—JOHN MILTON, Il Penseroso