QUESTION: 
Since there is no gravity in space why don't the planets just float around
in space?
ANSWER from Ed Colbert on March 20, 1996:
>
>Actually there IS gravity in space, in fact gravity is EVERYWHERE!!!
>
>The gravity that you feel when you walk around on the ground is caused by
>the mass of the Earth (our planet).  When you get close to large things
>like planets or stars you feel their gravity.  So, when you go out in
>space, the EARTH GRAVITY is weaker.
>
>BUT, the SUN GRAVITY is much stronger and it makes the planets rotate around
>the sun, just like the moon rotates around the EARTH from the EARTH GRAVITY.
>
>Isn't that fascinating?
>