I saw a documentary on ABC called Journey to the planets, this one episode being about Neptune and Uranus. I don't know how long ago this doco was made, so there may be updates from it. In it, they talked about Uranus's magnetic field being skewed differently to the other planets, and that they we're not sure as to what was causing it. Also because they couldn't find proof of there even being a solid core, and hence no iron in that core, that they couldn't explain the magnetic field to begin with. But they said this all after having said that the gas under the surface is pressurised to something more like a liquid -which made me think of plasma in a Sun. But wouldn't that explain the magnetic field? Plasma is generally charged, and when a charge moves it creates a magnetic field. Even Uranus's unusual magnetic field may be explainable due to the creation of the magnetic field not being due to liquid iron in a solid core, but to a liquid gas, which possibly acts differently. Of course, I know there isn't plasma in Uranus, the pressures involved couldn't possibly be enough, but maybe it's related? These are all just guesses made from the physics I have done, and based on what they said in the mini-series. I would love to know what everyone else thinks, or if there have been any breakthroughs in the area since the show was made.