Mountains on the Moon

Galileo demonstrated the existence of mountains on the Moon (Figure 1) . Some Aristotelian physicists taught that the shading of the Moon was internal, its surface as smooth as a marble.

Galileo inferred the existence of a lunar atmosphere from the fact that the mountains are not seen on the edge of the lunar disk.

Exhibit credit: Kerry Magruder, with the assistance of , Marilyn B. Ogilvie, Duane H. D. Roller.