Earth-Moon Distance Increasing
Is distance between earth and Moon increasing? Why?
Yes, about 3 meters per century. The Earth has been slowly moving
away. As a result the Earth's rotation is slowing down very slowly as well.
Yes, the Earth-Moon distance is increasing. We know this because the
Apollo Astronauts placed reflective mirrors on the moon from which
we can bounce of lasers from the Earth and measure the time it takes
for the light to travel back and forth between the Earth and the
Moon. Successive measurements show that the Earth-Moon distance is
This is counter to the idea that the gravitational forces between
the Earth and the Moon should bring the two bodies together and is
taken to mean that there are other forces at work here. One of the
suggestions is that the Moon was a product of a collision between
the proto-Earth and another celestial object which produced the
current Earth and the Moon. This hypothesis then suggests that in
the early history of the Earth and the Moon, the two bodies were
very much closer to each other and the collision forces that created
the two bodies is what is forcing them farther apart from each other.
Greg (Roberto Gregorius)
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Update: June 2012