Hi James,

That is a great question!

Not all of the planets in the solar system are magnetized, meaning that they have a strong, global magnetic field that can be measured in space or anywhere on the surface of the planet. The planets with strong magnetic fields are Mercury, Earth, Jupiter, Saturn, Uranus, and Neptune. Venus does not appear to have any kind of magnetic field at all. Mars has localized areas of magnetized rocks, which suggest that Mars may have had a strong, global magnetic field sometime in the past, even though it does not today.

The magnetic fields of Earth and Jupiter are close to dipole fields (two poles), which means they have a north and south pole and the field is sort of like that of a bar magnet. Uranus and Neptune have more complicated magnetic fields with strong quadropole (four poles) components (you can see a picture here - http://www.windows2univer...tipole_fields.html).

The equatorial magnetic field strength of Mercury is about 250 nT (nanoteslas). Earth's equatorial magnetic field strength is about 31,000 nT, so the Earth has a much stronger field than Mercury. At the top of Jupiter's clouds, the magnetic field is 14 times greater than that of the Earth's surface magnetic field. Jupiter's magnetic field is so strong that the Sun could fit inside Jupiter's magnetosphere. The equatorial magnetic field strength of Saturn is about the same as that of Earth, while Uranus and Neptune haver slightly weaker surface magnetic fields.

Kris