1. Underworld Character Kicked Out of Planetary Family
2. Hogan J., Nature442, 965 (2006).
3. Levison H. “A hand-waving derivation of planethood” (2006); www.boulder.swri.edu/∼hal/planet/.
4. Satellites with planet characteristics such as Saturn's moon Titan would be distinguished as “planetary satellites ” but could also be planets under a definition not requiring that they orbit a star.
5. The IAU defines “dwarf planets” as round objects that have not cleared their orbits but explicitly says they are not planets which confuses many.