Newton, Galileo, Henry Cavendish, and Eratosthenes contributed to this amazing calculation. ??? This calculation is done using Newton's Law of Gravity, which formulates the attractive force (gravitational force) that two masses exert on each other: F=GmM/r2 In Newton's equation, F is the gravitational force, G is a constant of proportionality, M and m are the two masses exerting the forces, and r