At 100km, the gravitational acceleration is actually higher than at the surface. http://www.wolframalpha.com/input/?i=gravitational+acceleration+at+100km+below

At 100km, the gravitational acceleration is actually higher than at the surface. http://www.wolframalpha.com/input/?i=gravitational+acceleration+at+100km+below+surface http://www.wolframalpha.com/input/?i=gravitational+accelerat... In fact, it increases until 3500km below the surface (2800km radius). http://en.wikipedia.org/wiki/Gravity_of_Earth#mediaviewer/File:EarthGravityPREM.svg http://en.wikipedia.org/wiki/Gravity_of_Earth#mediaviewer/Fi...