Discussion Post – What defines a Planet?
From its discovery in 1930 up until 2006, Pluto was considered the
ninth planet in the Solar System. After the International Astronomical
Union revised and solidified the definition of a planet, poor Pluto was
demoted to “dwarf planet,” with the discovery of similar icy bodies
beyond Neptune. A similar reclassification occurred for Ceres in the
Do you think Pluto should still be designated a planet, or not? What
about the other four classified dwarf planets? Consider the IAU
definition and the characteristics of both planets and small bodies in
the Solar System, and defend your position.