What do curveballs and satellites have in common?
They both spin to stabilize their motion. Curveballs curve because the pitcher puts a spin on the ball. As the ball spins through the air the motion of the air gives the ball a little push in one direction and the ball curves. It also gives the ball stability. When a pitcher throws a knuckleball it bounces all over the place. Satellites spin to make them easier to control. If you set a satellite spinning the axis of the spin stays pointed very accurately. If the satellite is designed not to spin even a small force can cause it to start wobbling.
