Why was it so surprising that Voyager 2 discovered magnetic fields associated with Uranus and Neptune?

Question

How do their magnetic fields differ from the magnetic fields of Earth, Jupiter and Saturn?

Answer 1

both are tilted dramatically from the axis of the planet, 47 and 60 degrees

Answer 2

Hi. I did not know this but magnetic fields require a metallic core. Jupiter is massive enough to have a metallic hydrogen core. They must either have a core of iron or metallic hydrogen, I guess.