What type of definition replaced the older, subjective size estimates for planetary status after 2006?

Answer

Dynamic dynamical definition

The overhaul of the planetary definition implemented by the IAU in 2006 represented a fundamental philosophical shift in astronomical classification. The previous system relied heavily on visual observation, subjective size judgments, and historical continuity. The new framework, however, moved decisively toward a dynamic dynamical definition. This new definition centers on the object's gravitational influence and its relationship to other bodies sharing its orbital zone. Instead of merely describing what a body looks like or where it generally resides, the new rules test whether the object is the dynamical 'master' of its orbital path. This rooted the classification firmly in orbital mechanics, demanding gravitational dominance rather than merely being a major orbiter or appearing round.

What type of definition replaced the older, subjective size estimates for planetary status after 2006?

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