Space is like liquid/water, but space has no friction. Water has a density. The planets have a density. The galaxies are like different vortexes and the gravitational pull is caused by the pull of the vortex. The vortex spins faster in the center and slower on the top/outside. So that's why gravitational pull is different on other planets/moons Density dictates where you fall in the galaxy/vortex and there are many vortexes throughout the universe. Theory.
