On 2007-10-15 11:14:20 -0400, "Bill" said:

Gravity always exists. At a LaGrange point, the gravity of one mass is
cancelled by the mass of another. So gravity has no effect on free
bodies at a LaGrange point, but gravity still exists.

How does one know it exists there? By measuring it?

By using it. There are a few satellites sitting in the vicinity of the
various Lagrange points.

Even there, the gravitational forces aren't exactly cancelled, but
exist in a dynamic balance.

--
Jere Lull
Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/