Q&A: General Astronomy and Space Science

Q:
How old is the moon?

A:
The moon may be 4.5 billion years old, formed by a collision between the Earth and a very large object. For a nice explanation of this, please see this NASA website:
http://lunar.arc.nasa.gov/history/lhistory.htm

However, it's important to note that we actually do not know how and when the moon formed! It is one of the mysteries of the Universe we hope to figure out in the future.