John Roberts, age 11, of St. Catharine for his question:

Why is there no air on the moon?

Our blanket of air cannot escape because it is held by the force of the eartht’s gravity. The power of gravity depends upon mass and the earth is massive enough to hold an atmosphere hundreds of miles deep. The moon is not massive enough to hold an atmosphere.

The enemy of gravity is speed. If a particle of air can travel fast enough, it can escape the pull of gravity and escape into space. We call this anti‑gravity speed escape velocity. On the earth, escape velocity is almost seven miles a. second. If a, molecule, a mouse or a mountain can travel that fast it can escape the pull of earthis gravity. On the moon, the escape velocity is only one and a half miles a second. Heat warms the air and makes its molecules travel faster. If the moon ever had air, the daytime temperatures would have speeded up the molecules fast enough to escape the moonts weak pull of gravity.