A Conversation for Ceres - Dwarf Planet

Slight Definitional Flaw?

Post 1


A dwarf planet is a celestial body that
(a) is in orbit around the Sun,
(b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape,
(c) has not cleared the neighbourhood around its orbit, and
(d) is not a satellite.

Any body that satisfies (a) cannot, strictly speaking, satisfy (d), because if it is in orbit around the Sun it is a satellite ... of the Sun.

Slight Definitional Flaw?

Post 2


It looks like we are getting into semantics here. However I will check and see hou the IAU defines satellite.

Slight Definitional Flaw?

Post 3


I didn't find it, however I seem to remember in some factsheet it said
A satellite is an object whose center of gravity falls within the surface of another object which is in solar orbit.
It went on to contrast our moon (which is not a dwarf planet because it has the center of its orbit within Earth) with Charon (whose center of its orbit is outside pluto). This fourth criteria was perhaps added to silence people who say that The moon , Titan, and Ganemede should be awarded the status of Dwarf Planet.

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