Wednesday, June 3, 2009


In 2006 Pluto was announced to be a dwarf planet because it did not meet the proper criteria for being a planet. International Astronomical Union (IAU) states that in the Solar System a planet is a celestial body that:
1. is in orbit around the Sun,
2. has sufficient mass to assume hydrostatic equilibrium (a nearly round shape), and
3. has "cleared the neighborhood" around its orbit.
Since Pluto does not meet the 3rd planet requirement it was deemed a dwarf planet. Since then the IAU has discovered a new and larger dwarf planet named Eris. Do you feel that it is necessary to classify Pluto as a dwarf planet for sake of science? OR Should we reclassify it as a planet for the sake of tradition? Please explain answer thoroughly and choose one definitive side.


  1. This is not an either/or question. There is an easy solution: establish dwarf planets as a subclass of planets. Dr. Alan Stern, Principal Investigator of NASA's New Horizons mission to Pluto, first coined the term "dwarf planet" to apply to small icy planets that are large enough to pull themselves into a round shape (hydrostatic equilibrium) but not large enough to gravitationally dominate their orbits. He never said that dwarf planets should not be considered planets at all. That was the nonsensical definition adopted by the IAU, in a process that violated its own bylaws. If we establish dwarf planets as a subclass of planets, then both Pluto and Eris are planets of the dwarf planet subcategory, as are Ceres, Haumea, Makemake, and Eris.

  2. If we were to keep with the sole definiton of hydrostatic equilibrium, the moon would be a planet. Gravitational domination is not only a valid definition, but a necessary one.