Astronomy Fun Fact #88

The footprints that Neil Armstrong and Buzz Aldrin left on the Moon are still there because there's no wind to blow them away.

There is a veeeery thin layer of gas around the moon that can almost be called an atmosphere, but is technically called an exosphere. This exosphere is so thin and so sparse that molecules rarely interact with each other.

Wind is caused by differences in temperature and pressure throughout an atmosphere. So since there's basically no atmosphere on the Moon, there's no wind.