A planetary dynamo generates a roughly dipolar magnetic field.
Charged solar-wind particles spiral along field lines instead of
crossing them, carving out a magnetosphere that shields the
surface — weaken the field or speed up the wind and more
particles punch through toward the poles.
The upstream boundary of this bubble is the bow shock: where
the field is strong the boundary sits far out and the wind is turned
aside smoothly, but as wind speed rises (or field strength drops) the
dynamic pressure of the incoming particles pushes that boundary — and
the whole magnetosphere — inward. That inward push is called
compression, tracked below as a percentage of how far the
boundary has been squeezed relative to its relaxed, field-dominated
position.
- Field strength — sets how far out the dipole field lines (and the bow shock) sit before the solar wind can penetrate.
- Solar wind speed — how fast and forcefully incoming particles push on the magnetosphere; higher speed compresses the boundary.
- Planet presets — one-click field-strength and spin defaults modelled loosely on Earth, Mars and Jupiter.
- Rotation rate — how fast the planet and its dipole field visualization spin about their axis.
In real life, Mars's core dynamo shut off billions of years ago,
leaving it with almost no global field — solar wind has been slowly
stripping its atmosphere ever since. Earth's much stronger field
maintains a wide magnetosphere that protects the atmosphere and
surface from that same bombardment.