The reality is we still don&#x27;t have good definitions for these objects.<p>&gt; They can&#x27;t, as one of the defining characteristics of a planet is having enough mass to be rounded under it&#x27;s own gravity.<p>The problem here is that &quot;rounded&quot; simply means &quot;roughly spheroid&quot;. It&#x27;s an imprecise term with no rules governing how far from a sphere the objects can deviate and still be considered planets or dwarf planets.<p>&gt; Dwarf planets have no such restriction.<p>It is that restriction that separates dwarf planets from large asteroids.<p>The distinction between planet and dwarf planet has to do with whether or not the object has cleared its orbit of other debris.