How would you tell that a planet or a moon had no atmosphere just by looking at the surface?

Answer:
If there are lots of craters, it means there is no significant atmosphere. The reason is that any craters will be eroded eventually, by the presence of an atmosphere.
First answer by Hilmarz. Last edit by Hilmarz. Contributor trust: 802 [recommend contributor recommended]. Question popularity: 1 [recommend question].