Every body is held together by two forces, its self-gravitation and its internal strength due to molecular bonding. Approaching another body, the sphere would begin to elongate toward that body. Finally, when the difference in gravitational force on the near side and far side of the former sphere exceeded the self-gravitation, the body would be torn apart. The distance from the larger body at which this disruption occurs is the so-called Roche limit, named for the man who first studied the problem. The differential gravitational effects of the Moon and the Sun are what raise the tides in Earth's oceans, and such forces are often referred to as tidal forces.
Solid bodies have intrinsic strength due to their molecular bonds.
Some 25 comets have been observed to split over the past two centuries. In other cases, two or more comets have been discovered in nearly the same orbit, and calculations have indicated that they were once a single comet. For example, the loss of material from an active comet, which tends to occur from a few localized areas, is bound to weaken it. It may be that a rapidly rotating comet can be weakened to the point where the centrifugal force is sufficient to cause large pieces to break off. The Kreutz family is the name given to many comets which closely approach the Sun from one direction in space.