English: Motion of a Ball on an oblate Spheroid, The brown ellipse represent a planet, a bit rust-coloured, no water on it, an oblate spheroid in shape and non-rotating (Of course this is strictly hypothetical, for a real celestial body that is non-rotating is drawn to a near-perfect sphere by its self-gravitation.)

This image shows this planet with on the North pole a large planar surface. Nothing is rotating here, in this section the non-rotating situation is discussed. If a ball is released somewhere on this planar surface, and friction is low enough, it will move towards the point of lowest gravitational potential. If the friction is very low, but not zero, then the ball will oscillate back and forth over the North pole for a while, and will eventually come to rest on the North pole, because that point is closest to the center of gravity.

Illustration for w:Talk:Coriolis effect page