Originally Posted by **HallsofIvy** topsquark specified that this was Gravity potential which is a field. "r" in his equation is the distance from the given mass to a point in that field. |

Note: that's true only under special circumstances, such as outside a sphere with symmetric body with uniform mass density. Inside the sphere its different. its also different for a binary star system. The gravitational potential above a spiral galaxy is nothing like that. But the gravitational field of all bodies can be found by adding up all the point particles that its made of by integrating.