An alternative to the dirty snowball model of comets

To be viable, a scientific theory or model must not be contradicted by observations or experiments. To be useful, a model must explain some phenomenon and aid the understanding of it. By these criteria, the Dirty Snowball model for the nature of comets is now on shaky ground. By contrast, the Satellite Model easily passes all these measures of the worth of a theory. Briefly, in the Satellite Model, comets consist of a cloud of asteroid-like debris of all sizes, which is gravitationally bound together. Comet tails are formed when solar radiation pressure drives gas and dust away. Each important physical characteristic is review of comets, and how it fits into each model.