Wednesday, 22 August, 2001

How the Moon was Created

Somebody at work pointed me to this article that describes a theory of how Earth's moon was created.  It's an interesting theory, but I hope those guys have more than a computer model and some wild speculation to go on.

The article says that the moon is thought to have been much closer to Earth, and the Earth and the moon continue to get more distant from each other by several inches (centimeters) a year.  The distance from Earth to moon is approximately 240,000 miles.  If its been moving away from Earth at the rate of 1 inch per year for 4.5 billion years, that means its moved about 71,000 miles.  I wonder what tides would have been like when the moon was only 170,000 miles away.  Since the effects of gravity are inversely proportional to the square of the distance, the moons gravitational effects on Earth at that distance would be approximately double what they are today.

One other tidbit.  The article implies that the moon moving away from the Earth is what causes the rotational period to slow.  Does this mean that if the moon were to disappear, the Earths rotation would stop?  I was under the impression that the slowing of the rotational period is at least partially an effect of the moons gravity, and as the moon moves away, its effects on the Earth's rotation would lessen.  Was I wrong?

There's another article on this topichere