Two demonstrators sit at either end of a rotating platform and toss a ball back and forth.  When viewed from the rest frame (when the camera is mounted to the ground), the ball follow a straight line but doesn’t reach its target because during the ball's flight the target rotates away. When viewed from the rotating frame (when the camera is mounted to the rotating platform), the ball appears to experience a force that pulls it away from the target. This curved trajectory in the rotating frame is known as the "Coriolis Effect", sometimes called the "Coriolis Force", though it disappears in the rest frame. The Coriolis Effect can be seen in many situations where rotating frames are encountered, especially meteorology and astronomy. Atmospheric systems, for example, often follow circular patterns due to the Coriolis effect. Airplanes and missiles appear to follow curved trajectories when seen by observers on Earth as the planet rotates underneath.