Did the Moon Once Have Company?

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Let’s face it: The Earth got a raw deal, moon-wise. Other planets have multiple moons with mythologically-inspired names, and here we are with just one lonely, unimaginatively named Moon. You can see the sadness on the face embedded in its surface.

The moon might not have always been so alone, however, Cosmos reports. Astronomers recently published a paper in Cornell University’s journal Icarus speculating that two asteroidal bodies, dubbed Trojans, may have formed 4.4 billion years ago, around the time the Moon we know came into being. The study uses mathematical modeling to show how the Trojans could remain stable in a gravitational equilibrium between Earth and the Moon, allowing them to orbit the Earth for a few million years. They were both tiny–probably about 100 kilometers in diameter–and would have appeared to Earthlings as two bright stars.

When these Trojans eventually left their orbits, the evidence suggests that they may have been among the debris that eventually slammed into the moon, creating the familiar pockmarks we see today. They also could have been burned up by the sun, or broken into smaller asteroids.

Image by joka2000, licensed by Creative Commons.

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