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Earth's Moon Page 2 notes

Movements of the Moon

· Elliptical orbit around Earth

· Perigee – When moon’s orbit is closest to the Earth (P-pretty close)



· Apogee - When moon’s orbit is farthest from the Earth (A-away)


· Moon actually moves eastward, though appears to move west

· Moon’s period of rotation is the same as its period of revolution around the Earth– 27.3 days

· This is why the same side of the moon always faces the Earth – we only see one side of the moon

Origins of the Moon

Three theories

 1) The moon formed millions or billions of kilometers away and was later captured by Earth’s gravity.

2) The moon formed from the same cloud of gas and dust that the Sun, Earth and the rest of our solar system formed from. The moon rocks lend support to this theory.

3) A giant asteroid (the size of Mars) hit the Earth and tore a chunk out of Earth’s surface. The Chunk is now our moon (stayed in orbit due to Earth’s Gravity.) The hole that was left on Earth is now the Pacific Ocean. This is also supported by moon rocks.


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