I appologize for any grammar or spelling errors. English is not my first language. I do my best. Given 2 objects in space, is there an equation that explains that one will, naturally and without any interference other than gravity, assume an orbital movement around the other? And does the same equation (or is there another for that end) describes the precise orbit? describing things like the shape of the orbit, distance and velocity of the orbiting body at any given point of the orbit, etc On a related subject, why are orbits so common? I'd assume (probably naively) that the most common form of gravitational interaction would be the less massive object being attracted by the more massive object in a trajectory that would lead to a collision. Why are there so many orbital behaviours in the universe, like pairs of stars, stars and their planets, planets and their satelites (including the man made ones here on Earth) and so on, instead of things just falling into other more massive things?