Why is there no air on the moon?
The Moon has no air because its gravity is too weak to hold an atmosphere. The gravity on the Moon is about six times less than the gravity on Earth, so any gases on the Moon (except for the very heaviest) would eventually float away into space, Because the Moon has no air, astronauts who go out onto the Moon’s surface must carry their own air supply. They must also wear helmets and protective clothing.
This has something to do with gravity, the pulling force that hugs us to the surface of the earth. The earth happens to be a sizable planet, very heavy for its size. The strength of its gravity depends on its size and weight. Actually, the earth’s gravity is strong enough to reach out and hold down our airy atmosphere, which reaches hundreds of miles above our heads. The moon is only about one quarter as big as the earth, and it is made of much lighter materials. This is why gravity on the moon is six times weaker than it is on the surface of the earth. Everything on the lunar surface weighssix times less than it does on the earth. And this weak gravity is not strong enough to hold on to an airy atmosphere. The gaseous molecules would escape and get lost in space.
