EARTH
In the literature: open
Why are Uranus's and Neptune's fields strongly tilted and multipolar?
In plain words
The magnetic fields of Uranus and Neptune are tipped far from the spin axis and lumpy, unlike those of other planets. This suggests the dynamo (the field generator) runs in a thin layer, but the interior is poorly known.
Precise statement
Voyager 2 measured dipole tilts near 59 and 47 degrees with strong quadrupole and octupole components. Determine whether a thin-shell dynamo in an ionic water-dominated layer above a stably stratified interior reproduces these fields, and what interior structure is required. An answer is a dynamo model consistent with measured field harmonics and with gravity and heat-flow constraints.
What would settle it
An orbiter mission measuring field harmonics, gravity and heat flow combined with dynamo models.