 ", more negative) gravitational potential energy than the sum of the energies of its parts when these are completely separated—this is what keeps the system in accordance with the minimum total potential energy principle.For a spherical body of uniform density, the gravitational binding energy "U" is given by the formula

where "G" is the gravitational constant, "M" is the mass of the sphere, and "R" is its radius.Assuming that the Earth is a sphere of uniform density (which it is not, but is close enough to get an order-of-magnitude estimate) with "M" = and "r" = m, then "U" = .