What keeps a satellite in orbit?
By Arielle Carrillo
Gravity pulls my marble down the elevated tube and holds the marble on the flat pan as it rolls forward on a straight line. On the elevated pan, the marble moves forward as it leaves the raised tube, but the earth's gravity tries to pull the marble down toward the lower end of the pan. The combination of the marble's forward motion and the downward pull of gravity causes the marble to move in a curved path.