Science: Earth Once Had Three Moons?

The already-mysterious moon gets weirder still.

Earth may once have had more than one moon, most probably two more, NASA scientists think.

Prevailing scientific consensus holds that the existing Moon was formed when a Mars-sized planet collided with the Earth 4.5 billion years ago, when the solar system was very young.

So much matter would have been thrown up into space that it recollected under its own gravity to form the Moon, which for millions of years would have glowed red-hot as the molten rock from the planetary collision cooled.

However, researchers Jack J. Lissauer of NASA's Ames Research Center near Mountain View, Calif., and John E. Chambers of the Carnegie Institution of Washington figure quite a bit of that ejected matter would have recollected into two other small moons at the so-called "Lagrangian points" or "Trojan points."

Those are fixed places in the Moon's orbit around the Earth where the gravity of both large bodies would keep smaller objects in stable positions.

...

Lissauer and Chambers figure the two small moons would have orbited Earth for about 100 million years before the slight gravitational tugs from the solar system's other planets sent them spiraling off course, either to crash into the Moon or Earth or to drift off into space.

Crashed into earth? Like, maybe a kill-the-dinosaurs sort of crash?

Thanks to Jack M.

posted by Ace at 02:43 PM

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