The Strange Spin of Uranus
Directional terms like north and south make sense here on Earth. The north and south axis of the Earth is relatively perpendicular to the plane of the Earth's orbit around the sun. Actually, Earth's axis of rotation is 23.5 degrees from the vertical. The variance from the vertical is what causes our seasons.
But imagine being on the planet Uranus. There you'd get really confused about north and south, because Uranus spins on its side. Its rotation is about 90 degrees off the vertical. This means that its polar axis points towards the horizon. But which axis? If it is spinning counterclockwise like Earth, we can easily fix one of the poles as the north pole. But most scientists think that it is actually spinning slightly less than 90 degrees. This would mean its rotation is retrograde, spinning clockwise. So actually we should be calling the south pole the north pole instead.
To make matters more interesting, Uranus' magnetic pole is not even close to its true pole. Scientists are split as to why Uranus rotates horizontally. A popular theory is that Uranus collided with a large planetary body in the early solar system that, in effect, knocked it on its side.
About the Author
Gene Mascoli, JD
Gene Mascoli is a founder and publisher of ScienceIQ.com. He holds a J.D. degree from the University of Santa Clara and a B.A. in English. In 1997 Gene launched ScienceMaster.com, an online science education portal where he brought together his love of writing with his interest in the sciences. Gene collaborated with David Gamon on the popular digital book “The Internet Guide to NASA on the Net” and has also produced two popular science CD-ROMs on astronomy and space science.