The moon likely started as a giant ball of magma formed from the remains of a collision by a Mars sized object with the Earth about four and a half billion years ago.
After the magma cooled, the moon's crust formed. Then between 4.5 and 4.3 billion years ago, a giant object hit near the moon's South Pole, forming the South Pole-Aitken Basin, one of the two largest proven impact basins in the solar system.
This marked the beginning of collisions that would cause large scale changes to the moon's surface, such as the formation of large basins.
Because the moon had not entirely cooled on the inside, magma began to seep through cracks caused by impacts. Around one billion years ago, it's thought that volcanic activity ended on the near side of the moon as the last of the large impacts made their mark on the surface.
The moon continued to be battered by smaller impacts. Some of the best-known impacts from this period include the Tycho, Copernicus, and Aristarchus craters.
So, while the moon today may seem to be an unchanging world, its appearance is the result of billions of years of violent activity.
The two-and-a-half minute video is available for viewing and downloading at: http://svs.gsfc.nasa.gov/goto?10930
The fully narrated video, as well as clips from each of the stops on the tour, are available to everyone in formats viewable on virtually any device.
To view the whole tour; go to: http://svs.gsfc.nasa.gov/goto?10929
iPad owners are also encouraged to download the NASA Viz app to see this and other NASA science stories updated twice a week. The story featuring Evolution of the Moon will be available Thursday, March 15.
To download the app, go to: http://svs.gsfc.nasa.gov/nasaviz/index.html
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