Are orbiting planets an example of perpetual motion?

I understand that perpetual motion is impossible, but I became confused when a friend of mine told me that the orbits of the planets is an example of perpetual motion. Will earth's orbit ever end, and whats wrong with his statement. I'm asking for a simple answer to 'disprove' my friends 'theory'.

Answer

Perpetual motion is a system that produces work (energy) while maintaining its state (which implies it can forever produce energy without changing state).

Orbiting planets are not a perpetual motion system. NOTHING we know of or can explain is a perpetual motion system.

Orbiting planets APPEAR to be a perpetual motion system, because the length of time needed for an OBSERVABLE (measurable) state change to occur is enormous (many, many, many, many lifetimes).