In
classical mechanics, the
Kepler problem is a special case of the
two-body problem, in which the two bodies interact by a
central force F that varies in strength as the
inverse square of the distance
r between them. The force may be either attractive or repulsive. The "problem" to be solved is to find the position or speed of the two bodies over time given their masses and initial positions and velocities. Using classical mechanics, the solution can be expressed as a
Kepler orbit using six
orbital elements.