2024-07-19 06:00:11
Scientists are proposing a new definition of the word “planet” to replace what they consider to be an outdated definition centered on our Sun. The current definition, established in 2006 by the International Astronomical Union (IAU), stipulates that one planet must orbiter around of Soleilwhich excludes many celestial objects discovered outside our Solar system.
A study to be published in the Planetary Science Journal argues for a definition broader, including bodies orbiting other stars. This proposal includes clear quantitative criteria to better define what a planet is, not limited to our Solar System. Professor Jean-Luc Margot of UCLA, lead author of the paper, will present this new definition at the IAU General Assembly in August 2024. Under the current definition, a planet is a celestial body orbiting the Sun, massive enough to be spherical and having cleared its orbit of debris. However, this definition excludes exoplanets and lacks precision, according to Margot and his colleagues. They propose a new definition based on the masseeliminating subjective debates about form.
The proposed new definition states that a planet is a celestial body that:
– Orbits one or more stars, brown dwarfs or stellar remnants;
– Has a mass greater than 1023 kg;
– Has a mass less than 13 Jupiter masses (2.5 x 1028 kg).
The authors used a mathematical algorithm to analyze the properties of objects in our Solar System, identifying distinct groups. They suggest that dynamic dominance and mass are key criteria for defining a planet. Objects massive enough to trigger the fusion thermonuclear of deuteriumthus becoming brown dwarfs, would not be planets.
The spherical shape, although commonly associated with planets, is difficult to confirm for distant objects. Therefore, the authors consider this characteristic impractical for definition. They believe that mass, which is easily measured, constitutes a more robust criterion.
Ultimately, the authors hope their work will initiate a discussion leading to an improved definition of what a planet is, although any official change to the IAU definition could take a few years.
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