Why would an observer out in space see the moon orbiting the earth rather than the earth orbiting the moon?

- The earth's gravity pulls on the moon, rather than the moon's gravity pulling on the earth
- The moon has much less mass than the earth
- The same side of the moon faces the earth
- The same force that pulls an apple to earth pulls the moon toward the earth

I think it's the 2nd option. Is that right?

Question

Why would an observer out in space see the moon orbiting the earth rather than the earth orbiting the moon?

- The earth's gravity pulls on the moon, rather than the moon's gravity pulling on the earth
- The moon has much less mass than the earth
- The same side of the moon faces the earth
- The same force that pulls an apple to earth pulls the moon toward the earth

I think it's the 2nd option. Is that right?

mrnood · Answer

Hmmmm - this again is an imprecise question.

Careful observation would show that the 2 bodies in fact orbit each other.

They orbit about their common centre of mass.

Because the mass of the earth is much bigger than that of the moon the centre of mass of the earth/moon combination is in fact just inside the earhts surface

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