Interplanetary Magnetism

[PlutonianEmpire]

I was laying on my bed earlier, and I was thinking...

How do worlds with a good magnetic field, like earth interact with each other?

For example, an earth-size planet with an magnetic field equal to earth approaches. When they get close enough, do they start acting like bar magnets, like, the magnetic pole of one body is attracted to the other pole of the other body, or does relative motion and/or gravity exceed the magnetic attraction of the two bodies?

[Malenfant]

gravity is generally much stronger than magnetism. There might be funky auroras as charged particles fly around the mangled interacting magnetic fields as the bodies approach, but it won't 'pull the planets together' at all.

[PlutonianEmpire]

Oh, ok. Even the axial tilts would be unaffected by the interacting magnetics?

[Malenfant]

Oh, ok. Even the axial tilts would be unaffected by the interacting magnetics?

They'd be more likely to be affected by tidal forces, and even that would be pretty low probability.

[PlutonianEmpire]

Thanks.

[selden]

If they're in constant contact (a moon with magnetic field orbiting a planet with one, for example) there are bound to be long term effects, even if the forces are small. Long term meaning like a million years...

[Malenfant]

If they're in constant contact (a moon with magnetic field orbiting a planet with one, for example) there are bound to be long term effects, even if the forces are small. Long term meaning like a million years...

I really doubt it - tidal effects in that case would be so much larger. Maybe if they both had the magnetic fields of neutron stars there'd be orbital effects (and I think you do get magnetic braking in such systems) but with the sorts of field strengths that planets generate it's not going to noticeably affect their orbits.

I think we'd be talking a few millimetres over *billions* of years in planetary cases.

[eburacum45]

I bet the interaction between a moon with a strong magnetic field with a primary also with a strong magnetic field would produce some interesting effects on the atmosphere of the moon. Amazing periodic aurorae and possibly even sputtering when the fields periodically reinforce each other and cancel each other out.