on this date in 1930 by Clyde Tombaugh (the planet, not Mickey's dog.) If you've kept up with recent events you know that this distant and diminutive body in the solar system has been reclassified by the International Astronomical Union (IAU) in 2006 to "dwarf planet" status.
I concur with the new ranking despite the upset Mr. Tombaugh's surviving relatives may feel due to this abrupt demotion. Simply put, if Pluto were discovered today it would certainly not be defined as a planet by the IAU. Remember, science is a continuous process of gathering new knowledge and reevaluating and reorganizing definitions and relationships.
Wednesday, February 18, 2009
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It is not correct to say that if Pluto were discovered today, it would not be defined as a planet. First, the demotion of Pluto was done by only four percent of the IAU, most of whom are not planetary scientists. It was immediately opposed in a petition of hundreds of professional astronomers led by Dr. Alan Stern, Principal Investigator of NASA's New Horizons mission to Pluto. You can find that petition here: http://www.ipetitions.com/petition/planetprotest/ It is important to note that many planetary scientists are not IAU members; therefore, the definition of planet should not be left solely up to the IAU.
ReplyDeleteThe IAU definition makes no sense in stating that dwarf planets are not planets at all. That is like saying a grizzly bear is not a bear. It also departs from the use of "dwarf" in astronomy, where dwarf stars are still stars and dwarf galaxies are still galaxies. Additionally, it defines objects solely by where they are while ignoring what they are. If Earth were in Pluto's orbit, according to the IAU definition, it would not be considered a planet either.
Many astronomers prefer a broader planet definition that includes any non-self-luminous spheroidal body orbiting a star. We can distinguish types of planets by subcategories such as terrestrial planets, gas giants, ice giants, and dwarf planets. However, the aspect of being spherical should be what defines an object as a planet. Spherical objects are in a state of hydrostatic equilibrium, meaning they are shaped by gravity rather than chemical bonds, with their own gravity pulling them into a round shape. By this definition, Pluto is most certainly a planet.
See how hot and bothered some people are about the status of Pluto! These points have all been made before, but still, the IAU does not define Pluto as a planet.
ReplyDeleteI wonder how science would progress if we clung to outmoded ideas and definitions? Biologists are constantly reorganizing the relationships between species based on new understanding in genetics.
And no one is saying a "grizzly bear is not a bear" but rather a grizzly bear is just one type of bear, just like Pluto (and other related objects) are one type of planet, in this case a dwarf planet.
Since when is science done by petition?
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