Definition of planet object can be irregular in shape, but beyond that point gravity begins to pull an object towards its own centre of mass until the object collapses into an ellipsoid. (None of the large objects of the Solar System are truly spherical. Many are spheroids, and several, such as the larger moons of Jupiter and Saturn and the dwarf planet , have been further distorted into ellipsoids by rapid rotation or tidal forces, but still in hydrostatic equilibrium.) However, there is no precise point at which an object can be said to have reached hydrostatic equilibrium. As Soter noted in his
Social gravity a manner "analogous in all cases, by which the center of gravity in the solar system" held the planets in their orbits. In making this analogy, Pownall's notion of 'social gravity' drew upon earlier visions of social cohesion, particularly ideas of sociability in eighteenth-century Britain. These ideas, in turn, were often predicated upon Stoic notions of cosmopolitanism, expressed by the key term oikeiôsis, in order to stress the "moral" imperative for like-minded humans to forge bonds dedicated to the common good. Social gravity Social gravity was an application of Newtonian gravity to the system of commerce influence. For instance, in