March 15, 2003
A: FROM MENTOR GENAH BURDITT IN CO
That's a great question. Gravity is a confusing concept to understand. Basically what it comes down to is there's no such thing as NO Gravity. It's really a matter of whose gravity is pulling on a body more.
All matter has gravity, the more massive = the more gravity. Therefore, there is a point of equilibrium between the earth and the moon (in other words, a point at which a body is effected equally by the moon's gravitational pull and the earth's.) There is a point of equilibrium between the earth and the sun (much closer to the earth than sun.) And so on and so on.
When you hear about micro-gravity or zero-gravity these are actually misnomers. When you see astronauts appearing to float in space it is because they are in free-fall towards the earth. Because the shuttle is also in free-fall at the same speed, they appear to be floating. The key is that the shuttle and ISS are moving forward fast enough (17,000 mph) that they never actually fall to the earth, they fall AROUND it as it turns. Make sense? See Isaac Newton's canon ball explanation for more.

One more thing...this one will really throw you for a loop but it's kind of fun.
Scientists have pondered for a long time, what is gravity? What is this invisible, mysterious force that seems to pull between every object in the universe? Current theories/mathematics suggest that gravity is actually a BEND in space-time, causing objects that get near it to curve or fall towards it.
Think about like this: space-time or the universe is a trampoline and the earth or some other body is a bowling ball sitting on top of that trampoline, causing it to sag. If you rolled a marble onto the trampoline, where would it end up?
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March 13, 2003
A: FROM MENTOR JOAN LUSK IN RI
the gravitational force between any two objects is inversely
proportional to the square of the distance between them : to 1/r^2
(one divided by r-squared) where r is the distance between their
centers. As r gets bigger and bigger the force gets smaller, but it
doesn't literally reach zero until r is infinite. But if you ask at
what distance from the earth does gravity become 1/100 of what it is
here at the surface, you can easily see that out in space 10 times as
far from the center (9 more earth's-radii away than the surface),
gravity will be down to 1/100 as much. And for any desired fraction
of the gravity at the surface you can find the corresponding distance.

Gravity acts at tremendous distances - influencing the motion of
galaxies all throughout the cosmos.
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A: FROM MENTOR DIANA DIONISIO IN CA
Gravity is due to the earths force and I'm not sure exactly what distance the earth's pull has no effect on a person's body. The force just gets smaller as a person or any object moves further from the center of the earth.
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A: FROM MENTOR SHEILA ENGLAND IN PA
Check out this web site:
http://newton.dep.anl.gov/askasci/wea00/wea00080.htm