* Low Escape Velocity: While the Moon's gravity is weaker, it's still strong enough to hold onto sand particles. The Moon's escape velocity is about 2.38 kilometers per second. This means a particle needs to be moving at that speed or faster to escape the Moon's gravitational pull. Sand particles, even the smallest ones, are nowhere near that fast.
* No Atmosphere: The Moon has practically no atmosphere. On Earth, wind can easily pick up and move sand, but on the Moon, there's no wind to blow the sand away. This lack of atmospheric resistance helps keep the sand in place.
* Micro-meteoroids: The Moon is constantly bombarded by tiny particles from space called micro-meteoroids. These impacts can actually help "pack" the sand particles together, making them more stable.
* Electrostatic Forces: The Moon's surface can become electrically charged by sunlight, which can create weak electrostatic forces that help hold some dust particles in place.
In short: The Moon's gravity, combined with the lack of an atmosphere and other factors like micro-meteoroids, are enough to keep the sand from escaping into space.
