Expert: Ed - 6/9/2006

Question
Why does the Earth rotates on its own axis while revolving around the Sun? Why does not the Earth stops rotating on its own axis?  

Answer
Mohit,
The Earth rotates because of leftover angular momentum, which existed in the primordial nebula from which our solar system was born.

This rotation does not stop because there is NO FRICTION to slow it down.  If our planet were rubbing up against a gigantic piece of sandpaper, maybe we would have slowed down a little over the past few billion years.  Actually, the moon is slowing us down a LITTLE because of tidal action, but not very much.

Here are some good links for further reading, from Cornell and NASA.
http://curious.astro.cornell.edu/question.php?number=416
http://www-spof.gsfc.nasa.gov/stargaze/StarFAQ1.htm#q26

Keep Looking Up!
--Ed