WIMP Orbiting inside Earth

This Demonstration shows a possible orbit of a hypothetical WIMP (weakly interacting massive particle) that is acted upon only by the force of gravity, moving inside planet Earth, with a given initial position and velocity. The orbit of the WIMP is shown in blue, with Earth shown as a green disk. All parameters are expressed in terms of meters and seconds. It is assumed that Earth's density is uniform, equal to its average value.