What Are the Dark Spots on the Moon?
The dark spots we see on the moon are really the moon’s large flat plains. The moon’s rugged surface is covered with mountains, craters, and great lava plains.
At full moon, the entire visible surface shines with reflected sunlight. But it is not the same brightness all over. The lighter-colored hills and mountains reflect more sunlight than the dark lava plains. We see the hilly areas as the bright white parts of the moon.
It’s fun to look at a full moon and imagine that two dark spots make the eyes, and other spots the nose and the mouth of a “man in the moon.” Which are actually craters filled with basalt, a very dense material.