Formation of the Solar System: Birth of Worlds
http://www.nasa.gov/audience/foreducators/topnav/materials/listbytype/YOSS_Formation_of_Solar_System/#.VaZ6uEthPwJ


When the solar system was young, planets were built as huge numbers of smaller bodies like asteroids collided with each other. In this lab, students model how over millions of years of collisions, planets like Earth grew to their present sizes.

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