Campbell+S++Wonders+of+Science

WONDER QUESTIONS: Why is the Earth round?
 * The earth has enough **gravity** and **mass** to pull itself into a sphere.
 * The earth is perfectly round.
 * One of the effects of mass is that it attracts other masses.
 * The force of gravity is tiny.
 * The planets have to be round to orbit the sun.
 * Objects about 1,000 km. in size can pull itself into a sphere.

Click here to find out more facts about the Earth. [| http://www.newton.dep.anl.gov/askasci/gen99/gen99251.htm]