The Birth of Eart's Moon: Giant Impact Theory

At the time Earth formed 4.5 billion years ago, other smaller planetary bodies were also growing. One of these hit earth late in Earth’s growth process, blowing out rocky debris. A fraction of that debris went into orbit around the Earth and aggregated into the moon.

The Giant Impact, as pictured in a painting by William K. Hartmann on the cover of Natural History Magazine in 1981. Copyright William K. Hartmann

Half an Hour After the Giant Impact, based on computer modeling by A. Cameron, W. Benz, J. Melosh, and others. Copyright William K. Hartmann

Five Hours After Impact, based on computer modeling by A. Cameron, W. Benz, J. Melosh, and others. Copyright William K. Hartmann

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