How has the earth's moon changed over time?

1 Answer
Jun 8, 2017

The Moon's orbit has changed over time.


Current theories are that the Moon was formed when another planet hit the earth. When the Moon was formed it would have be molten rock and much closer to the Earth and rotating quite quickly.

Over time the Moon cooled. As it has no atmosphere there was nothing to stop meteorites hitting the surface. Hence it has a large number of impact craters.

The Earth's gravity has tidal effects on the Moon. This has caused the Moon's rotation period to slow. It also has the effect of making the Moon's orbit get further from the Earth.

Over time the Moon became tidally locked to the Earth. This means that the Moon's rotation period is the same as its orbital period. This is why the Moon always shows the same face to the Earth.

As the Moon is quite large. It is also having tidal effects on the Earth. The ocean tides show that this is happening. This is slowing the Earth's rotation period. It is also moving the Moon's orbit further from the Earth.