Q&A: Our Solar System

Q:
Does Saturn's magnetic poles alternate over time? Is Chandra capable of detecting such a transition?

A:
It is a good idea, that the reason for the lack of X-ray "hot spots" on the magnetic poles of Saturn is due to a changing of polarity in the magnetic field of the planet. But it seems that Saturn does have a magnetic north and south pole and so the reason for the lack of X-rays on the south pole is a mystery.

You've probably read the Chandra press release on Saturn:
http://chandra.harvard.edu/press/04_releases/press_030804.html
but maybe you haven't read the press releases on other planets:
http://chandra.harvard.edu/photo/category/solarsystem.html.
In particular, you may want to look at the release on Jupiter - the Chandra image shows clear polar hot spots. The data on Venus show it lacks hot spots, but we'd expect this to be due to the lack of a magnetic field on that planet.

So, the answer is, it is a mystery! Hopefully Chandra will help solve it some day. It may be that the magnetic fields are getting slowly weaker, as the Earth's are, but it seems they are not weak enough to explain the lack of emission. Please stay tuned to the Chandra web pages since we have just completed a long observation of the Earth, and if the Earth does not show hot spots then your idea might be right. We'd have to find out the difference in magnetic field strength between Saturn and the Earth to check on this.