The gravitational potential at a point due to the gravitational field of a body of mass M is equal to the work done in taking a body of unit mass from infinity to that point. It is customary to take the gravitational potential at infinity to have the value zero. If the body of mass M is taken to be a sphere, then the gravitational potential at a distance R from the centre of the sphere is given by −GM/R, where G is the gravitational constant. The significance of the negative sign is that the potential at infinity has a higher value than it does near the body.