Neptune’s satellites all travel in one direction with the strange exception of Triton’s retrograde orbit. Triton is believed to have been a small planet like Pluto until it was “captured” by Neptune, instead of being a natural by-product of Neptune’s formation.
Further, due to Triton’s retrograde orbit, Neptune’s gravitational pull is causing the moon’s orbit to degrade. Astronomers in some far distant future, will be able to witness one of two incredible displays of planetary destructiveness. Neptune will either cause Triton to break apart, causing the largest moon to become debris or another ring around the planet. Or, the more extreme display of Triton colliding into Neptune may occur.
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This entry also posted in the American Military University Introduction to Astronomy newsgroup.