The History of the Moon

Using samples brought back from the Apollo astronauts, we can estimate the age of moon rocks through radioactive dating (see your text for details). So what do we get for the ages of moon rocks?

Lunar Highlands: 3.9-4.5 billion years (Gyr) old
Lunar Maria: 3.1-3.8 billion years (Gyr) old

Compare this with the oldest Earth rocks: 3.7 Gyr.
And compare this to the age of the Sun: ~5 Gyr.

So what have we learned? A sketch of lunar history:

Moon formed 4.5-4.6 Gyr ago
Early in the moon's history, its surface was hot and molten.

lack of volatile elements in rock
Gabbro rock - slowly cooling magma

Meteoric bombardment strong 3.8 - 4.5 Gyr ago
Major observed impact basins formed 3.8 - 4.0 Gyr ago

ie Mare Orientale
Could impact basins have formed earlier?

Volcanic flooding of basins happened 3.1-3.8 Gyr ago

we see evidence of volcanic flows
Basaltic rock - rapid cooling

Cratering rate much lower since about 3.8 Gyr ago

Some new craters have formed since.

What does this tell us about the solar system?

When did the planets coalesce?
What were conditions like in the early solar system?
When were the planetesimals largely "cleaned out" of the solar system?

But what about the formation of the Moon? How did it get there?