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Tuesday, July 28, 2009
Is Pluto a planet after all?
Poor Pluto was demoted, to the dismay of its many fans, but it could soon be returned triumphantly to full planet status.
Pluto did not stop being a planet because 424 astronomers made a controversial decision and adopted a vague, unusable planet definition. The requirement that an object "clear its orbit" was concocted specifically to exclude Pluto and keep the number of planets in our solar system low. The IAU definition makes no sense in stating that dwarf planets are not planets at all, a departure from the use of the term "dwarf" in astronomy, where dwarf stars are still stars, and dwarf galaxies are still galaxies. Also, the IAU definition classifies objects solely by where they are while ignoring what they are. If Earth were in Pluto's orbit, according to this definition, it would not be a planet either. A definition that takes the same object and makes it a planet in one location and not a planet in another location is essentially useless.
The IAU should take responsibility for the highly flawed definition adopted by only four percent of its members, most of whom are not planetary scientists, in 2006. However, the IAU should not be viewed as the sole authority on the definition of planet. Many planetary scientists do not belong to the IAU. Should they not have a say in this matter? Something does not become fact simply because a tiny group that calls itself an authority says so. It is significant that hundreds of planetary scientists led by New Horizons Principal Investgator Alan Stern immediately signed a formal petition opposing the IAU definition.
There are other venues through which a planet definition can be determined, such as last year's Great Planet Debate at the Johns Hopkins University Applied Physics Lab. Audio and video proceedings from this far more balanced conference, which I was fortunate to attend, can be found at http://gpd.jhuapl.edu/ . You can also read more about this issue on my blog at http://laurele.livejournal.com .
Poor Pluto was demoted, to the dismay of its many fans, but it could soon be returned triumphantly to full planet status.
1 comment:
Pluto did not stop being a planet because 424 astronomers made a controversial decision and adopted a vague, unusable planet definition. The requirement that an object "clear its orbit" was concocted specifically to exclude Pluto and keep the number of planets in our solar system low. The IAU definition makes no sense in stating that dwarf planets are not planets at all, a departure from the use of the term "dwarf" in astronomy, where dwarf stars are still stars, and dwarf galaxies are still galaxies. Also, the IAU definition classifies objects solely by where they are while ignoring what they are. If Earth were in Pluto's orbit, according to this definition, it would not be a planet either. A definition that takes the same object and makes it a planet in one location and not a planet in another location is essentially useless.
The IAU should take responsibility for the highly flawed definition adopted by only four percent of its members, most of whom are not planetary scientists, in 2006. However, the IAU should not be viewed as the sole authority on the definition of planet. Many planetary scientists do not belong to the IAU. Should they not have a say in this matter? Something does not become fact simply because a tiny group that calls itself an authority says so. It is significant that hundreds of planetary scientists led by New Horizons Principal Investgator Alan Stern immediately signed a formal petition opposing the IAU definition.
There are other venues through which a planet definition can be determined, such as last year's Great Planet Debate at the Johns Hopkins University Applied Physics Lab. Audio and video proceedings from this far more balanced conference, which I was fortunate to attend, can be found at http://gpd.jhuapl.edu/ . You can also read more about this issue on my blog at http://laurele.livejournal.com .
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