Just a little fleshing out of previous answers... F=Gm1m2 / r2 states that gravity is proportional to the product of the two masses (m1 and m2), and inversely proportional to the square of the distance (r) between their centers of mass. (G) is the gravitational constant in this equation. Problem is that as distance increases, the force decreases but is still existant. Additionally, the force, whatever it turns out to actually be, acts at or near the speed of light (c)...