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Sunday, January 04, 2009

The Battle for Planet Pluto Redux

Entrance to the Lowell Observatory.
Mark V. Sykes, director of the Planetary Science Institute in Tucson, Arizona, hopes to get the 2006 ruling by the the International Astronomical Union (IAU) meeting in Prague overturned at the next general assembly meeting of the group to be held in Rio de Janeiro in August reports The Indpendent, UK [video] and [Sykes commentary]. This debate will certainly be one of the most significant planetary battles of 2009.

First discovered at the Lowell Observatory in Flagstaff, Arizona by young astronomer Clyde Tombaugh, Pluto was officially named and labeled as the ninth planet by the International Astronomical Union in 1930. Its name was based on the Roman god of the underworld, Hades and also rumored to be the initials of the man who carved the path to discovery: Percival Lowell (P.L.uto).

The NASA New Horizons mission is enroute to Pluto with a flyby set for July 2015 [Video Mission Update].

1 comment:

Laurel Kornfeld said...

The IAU ruling on Pluto is one that begs to be overturned. It was made by only four percent of the group's membership, most of whom are not planetary scientists, in violation of the IAU's own bylaws. The planet definition they adopted was immediately rejected by an equal number of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA's New Horizons mission to Pluto.

There are several reasons why the IAU definition and subsequent demotion of Pluto make no sense. First, the definition states that a dwarf planet is not a planet at all. That's like saying a grizzly bear is not a bear! Second, the definition classifies objects solely by where they are while ignoring what they are. If Earth were placed in Pluto's orbit, according to the IAU definition, it would not be a planet either.

Astronomers who oppose the IAU decision believe we should keep the term planet broad enough to encompass any non-self-luminous spheroidal object orbiting a star. We can then distinguish different types of planets through using subcategories such as terrestrial planets, gas giants, ice giants, dwarf planets, hot Jupiters, super Earths, etc. Using this definition, our solar system currently has 13 planets: Mercury, Venus, Earth, Mars, Ceres, Jupiter, Saturn, Uranus, Neptune, Pluto, Haumea, Makemake, and Eris.