Earth-Theia

This simulation shows the hypothesized collision between the Earth and Theia about 4.5 billion years ago.

Theia is a hypothesized ancient planet in the early Solar System that according to the giant impact hypothesis collided with the early Earth. Theia was about the size of Mars, and had it not collided with the Earth with a glancing blow, it could have destroyed the Earth. Eventually Theia's debris gathered together around the Earth to form what was the early Moon.

This simulation shows a possible collision between the Earth and Theia that leaves much of Theia's outer material in orbit around the Earth. The time that is displayed in the bottom-left corner is in minutes, and the Earth is left with a much reduced rotation period of about five hours. The particles comprising the Earth and Theia are color coded as follows:

• Green - Earth's core
• Blue - Earth's mantle
• Red - Theia's core
• Yellow - Theia's mantle

The color coding in this simulation shows that much of Theia's mantle ends up in orbit around the Earth, with Theia's core and remaining mantle being added to the Earth. The Earth's core remains hidden throughout.

The position of Theia can easily be adjusted to change the angle of Theia's impact and the consequences of the collision. This is most easily done by editing the Theia sub-particle that is visible in the structure window, changing the three components of the absolute position by a few hundred or a few thousand kilometres to see what effect it has.

Since different computers run at different speeds, you may need to edit the evolution time step to get the simulation to run at an acceptable rate.

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