What defines a dwarf planet?

A dwarf planet is defined specifically as a celestial body that orbits the Sun, is massive enough to be rounded by its own gravity, but does not have the gravitational dominance necessary to clear its orbital path of other debris. This definition is essential because it distinguishes dwarf planets from full-fledged planets, which do meet the criteria of clearing their orbits.

Dwarf planets often share their orbital regions with other objects of similar size, leading to a diverse environment of celestial bodies in their vicinity. Notable examples of dwarf planets include Pluto and Eris, which exhibit this characteristic of not having cleared their orbit of other debris.

The other options do not align with the established definitions in astronomy. For instance, the notion that a celestial body is incapable of supporting life does not pertain to its classification as a dwarf planet. Similarly, the inability to hold a stable orbit is contrary to the definition, as dwarf planets indeed have stable orbits but do not clear them. Finally, the characteristic of clearing an orbit is essential for distinguishing between planets and dwarf planets, further emphasizing why the correct classification focuses on that inability.