The gravitational force between 2 objects depends on the masses of the objects and the distance between them. Links are provided. Newton's Law says, Force = Gravitational constant x mass of 1st object x mass of 2nd object / distance squared. F=Gm1m2 / d2 Where G=6.672 x10-11 Nm2/kg2 What this means in plain English is that the greater masses pull more on each other more than smaller masses, and the force decreases exponentially as distance increases.