The Tezber Planetary Evolution Model was a scientific model used by Federation scientists in the 24th century for describing the evolution of a planetary system. There were at least two models in existence by the 2340s.
In that decade, when the USS Berlin surveyed the long range comets in the Minos Korva system, they discovered an anomalous population of a specific class of rocky methane ice bodies. It was nearly 12% greater than results predicted by the models. (TNG-R: "Chain of Command, Part II")