[X] My Assistant

[Chmee]

A question that has bugged me for a long time is how planets capture asteroids, etc into an orbit. My understanding of orbital dynamics is that a body approaching a planet would need to be "braked" in order to be captured into orbit. In the same manner that our space probes use their rockets to slow them down enough or they would shoot past.

So for moons like Triton, Deimos, and Phobos (as well as the small, distant moons of Jupiter/Saturn) how were they captured? What provided the braking?

[dvandorn]

Gravity. In specific, gravity from a third (and even fourth or fifth) bodies. Around Mars, I'd guess that Jupiter generated a gravitational resonance that braked Diemos and Phobos enough to be captured. Tidal influences can then work to circularize the orbits.

I find it fascinating that, according to one current theory, Uranus and Neptune may have formed *between* Jupiter and Saturn. I can just image the gravitational resonances that must have disturbed the entire Solar System when those two giants were flung out into the outer reaches...

-the other Doug

[ljk4-1]

Gravity.  In specific, gravity from a third (and even fourth or fifth) bodies.  Around Mars, I'd guess that Jupiter generated a gravitational resonance that braked Diemos and Phobos enough to be captured.  Tidal influences can then work to circularize the orbits.

I find it fascinating that, according to one current theory, Uranus and Neptune may have formed *between* Jupiter and Saturn.  I can just image the gravitational resonances that must have disturbed the entire Solar System when those two giants were flung out into the outer reaches...

-the other Doug

Those moons are the leftovers from a Kardashev Type 2 Civilization astroconstruction project that had to be abandoned when the Galactic Empire switched ruling political parties.

Apparently they didn't count all the votes on Floridon 12 and Ohyox 3 until it was too late to reverse the decision.