Magnetic field evolution. The viewpoint is looking onto the nightside of the planet. Top row shows field lines for M2b2, with color representing the toroidal field magnitude, with red/magenta positive (with maximum of 5 G), blue negative (with minimum of −5 G), and yellow representing values between ±1 G. Middle and bottom rows show field lines for M7f1b1 and M7f1b2, respectively. Again, color represents toroidal field strength, with red/magenta positive with maximum of 260 G, blue negative with minimum −260 G, and yellow representing field strengths in the range ±20 G. Times are different for each model and are meant only to give a qualitative picture of magnetic field evolution.