Did Earth once have multiple moons?
The ancient catastrophe that gave birth to the Moon may have produced additional satellites that lingered in Earth’s skies for tens of millions of years.
A new model suggests moonlets may have once occupied the two Earth-Moon Lagrangian points, regions in space where the gravitational tug of the Earth and the Moon exactly cancel each other out. Objects trapped in these points are called Trojans and can remain stationary forever if left undisturbed.
Scientists think the Moon was created when Earth was struck by a Mars-sized object some 4.5 billion years ago.
…
Once captured, the Trojan satellites likely remained in their orbits for up to 100 million years, Lissauer and co-author John Chambers of the Carnegie Institution of Washington say. Then, gravitational tugs from the planets would have triggered changes in the Earth’s orbit, ultimately causing the moons to become unmoored and drift away or crash into the Moon or Earth.
Full Article: NewScientist
While I have heard the idea of a Mars sized planet crashing into the Earth to create the moon, I have never heard there may have been multiple moons for a period of time. I think it would be fascinating to have multiple moons to be able to visit instead of just one. While they may not have been very large, it would probably have been akin to visiting something like an asteroid.