Magnetic fields
The magnetic fields of
Earth(a), Uranus(b), Neptune(c) and the new numerical model(d). Blue regions are where field is entering the planet and orange
regions are where it is leaving the planet. Notice how the Earth's
field looks similar the field produce by a bar magnet (all field lines
leave one hemisphere and enter the other) whereas Uranus' and Neptune's
fields are more complex. The numerical model shows a similar complexity
to the fields of Uranus and Neptune (image credit: S Stanley 2004).