Possible theory on why Mercury and Venus have no moon, Clues from Earth and Mars moon orbits Options

[Antdoghalo]

I think i know why Mercury and Venus have nothing orbiting them.

You know how our moon and Deimos are slowly getting farther from Earth and Mars.
And Phobos is getting closer to Mars and will impact it eventually.

Phobos orbits in less than a Martian day.
Deimos and our moon orbit slower than there parents rotation.

Maybe Mercury and Venus consumed there moons because the slow rotation of those planets allowed tidal forces with any moon that orbited them to spiral inward and eventually impact them.

[ngunn]

Maybe there was originally a moon in a synchronous orbit for who knows how long, then an impact disrupted it leaving two major fragments, one outside and one inside the synchronous orbit. One would then start spiralling outward and the other inward.

[Greg Hullender]

Maybe there was originally a moon in a synchronous orbit for who knows how long, then an impact disrupted it leaving two major fragments . . .

Seems unlikely. They certainly don't LOOK like two halves of the same whole.

--Greg