Don't you need erosion, such as rain, to make dust? Or is it the meteors and asteroids that are making the dust on the Moon and Mars?
-
Yes, some dust was created by meteor strikes and asteroids , but by far the majority of dust on Mars is created by wind friction. Winds on Mars approach 700 miles per hour. Also, there is evidence that water was on Mars as little as several thousand years ago. The dust doesn't have to be new.
-
Wind makes erosion too. There have been huge dust storms on Mars probably since the liquid water evaporated. Blowing dust erodes even hard rock.
-
Wind and gravity create dust too!