Nov 15, 2015 04:29 AM
An Astronomer Proposes a New Mathematical Definition for What Counts As a Planet
EXCERPT: [...] The IAU’s famously vague definition, where a planet is “a celestial body that (a) is in orbit around the sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and © has cleared the neighborhood around its orbit,” has since come under fire from a number of astronomers who feel that such a loose definition hardly works for classification in our own solar system, to say nothing ofthe thousands of exoplanets that have been discovered since Pluto’s demotion.
In an attempt to solve this definitional crisis, UCLA planetary scientist Jean-Luc Margot proposed a new method for defining planets at a meeting of the American Astronomical Society on Thursday, the full outline of which is forthcoming in the Astronomical Journal. Elegant in its simplicity, Margot’s mathematical schemata allows for a quantification of the third element of the IAU’s definition, which would allow astronomers to utilize the definition to classify all exoplanets.
[...] There is still no word on whether the IAU will consider Margot’s criteria for mathematically defining planets, however there is one interesting result of his formula that might make it a tough sell at the next IAU generally assembly in 2018. According to his schema, Earth’s moon is above the critical mass necessary to qualify as a planet, technically making the Earth and moon binary planetary system. This might not be a fatal blow to his proposal however, given another definitional conundrum faced by the IAU....
EXCERPT: [...] The IAU’s famously vague definition, where a planet is “a celestial body that (a) is in orbit around the sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and © has cleared the neighborhood around its orbit,” has since come under fire from a number of astronomers who feel that such a loose definition hardly works for classification in our own solar system, to say nothing ofthe thousands of exoplanets that have been discovered since Pluto’s demotion.
In an attempt to solve this definitional crisis, UCLA planetary scientist Jean-Luc Margot proposed a new method for defining planets at a meeting of the American Astronomical Society on Thursday, the full outline of which is forthcoming in the Astronomical Journal. Elegant in its simplicity, Margot’s mathematical schemata allows for a quantification of the third element of the IAU’s definition, which would allow astronomers to utilize the definition to classify all exoplanets.
[...] There is still no word on whether the IAU will consider Margot’s criteria for mathematically defining planets, however there is one interesting result of his formula that might make it a tough sell at the next IAU generally assembly in 2018. According to his schema, Earth’s moon is above the critical mass necessary to qualify as a planet, technically making the Earth and moon binary planetary system. This might not be a fatal blow to his proposal however, given another definitional conundrum faced by the IAU....