Venus and Uranus are the two planets in the solar system that orbit the Sun with their north poles pointed in the opposite hemisphere from the other planets. Uranus has its pole pointed 8 degrees below the plane of the ecliptic in the southern ecliptic hemisphere; Venus has its pole located 87 degrees below the ecliptic plane so that it is only 3 degrees from the south ecliptic pole. If this were the Earth, the above picture would show our north geographic pole flopped to the bottom of the picture, and Earth would also rotate in the same backwards or 'retrograde' sense as Venus does.
The reason that so little mention is made of this is that for Venus, so much else is known about the planet that this fact gets crowded out. Also, no one really knows why Venus, and Uranus for that matter, have their rotation axis cocked in such peculiar orientations. The best ideas we have, have to do with planetary collisions with a large body just before these two planets were formed 3-4 billion years ago.
Copyright 1997 Dr. Sten Odenwald
Return to Ask the Astronomer.