A lesser known fact about our moon is that it is not a satellite of the Earth in the sense that Jupiter or Saturn have moons.
There are two reasons behind this -
i) The effect of the gravitational attraction of the Earth on the moon is far smaller than the effect of the gravitational attraction of the Sun on the moon. The Earth and the Moon are more accurately described as double planets circling the sun.
- if either the Earth were to suddenly disappear, the Moon would keep on orbiting around the Sun. On the other hand, if Jupiter were to suddenly disappear, its moons would go flying in every direction.
ii) The moon orbits the Earth in a plane aligned with the other planets of the solar system, rather than in an equatorial plane of the Earth, which would tend to be the case with traditional satellites.
So the take home message is that The Moon is not a moon! (but rather the Earth's partner in a double planet system)
Source - Discover magazine ... erm ... one of the issues in 2000 ...