Colliding Worlds

Over the past decades, several hypotheses have been proposed to explain how the Moon came to be. The current leading hypothesis of Moon formation is called the giant impact hypothesis. It states that a protoplanet collided with Earth about 4.5 billion years ago, while Earth was still forming.

The colliding protoplanet, named Theia, was vaporized by the energy of the impact. The steep, off-center angle of the impact mixed the materials from both objects, splashing a significant amount of the molten material from Earth and Theia into orbit around Earth. The orbiting material subsequently cooled and accreted to form a Moon made of mostly Theia material.

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The video shows a simulation of the hypothesized impact, based on numerical data. Note that the Earth and the Moon looked vastly different than they do today.

Take Notes

Based on the simulation, describe the impact in your own words. Include descriptions of the angle of the impact and the motions of the objects after the impact. Replay the video as necessary.