What is the true definition of a planet? Is it possible that a more refined definition will emerge in the future? Recent Research Published in Planetary Science Journal They hope to work with a team of researchers from the U.S. and Canada. Investigating the possibility of a new definition of “planet”.
The study has the potential to challenge the long-standing definition set by the International Astronomical Union (IAU). IAU Resolution B5 In 2006, Pluto was demoted from a “planet” to a “dwarf planet.”
Here, Universe Today discusses this surprising research with the study’s lead author. Dr. Jean-Luc MargotWe asked Dr. Margot, a professor in the Department of Earth, Planetary and Space Sciences at the University of California, Los Angeles, about his motivation for the research, its key findings, the steps the IAU needs to take to implement his new definition, and whether Pluto should be reclassified as a planet.
So what was the motivation for this study?
“IAU Resolution B5 is problematic because it’s vague, it excludes exoplanets, and the problems are not going to go away on their own,” Dr Margot told Universe Today.
“Our community and the general public deserve better definitions for key astrophysical terms like ‘planet’ and ‘moon.’ We’ve had 18 years to identify the issues and consider possible ways forward. There is every reason to believe that 2024 will be better poised to produce a better outcome than 2006.”
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According to IAU Resolution B5, the current definition of a planet is:
(a) It revolves around the Sun.
(b) Its mass is sufficient to overcome the rigid body forces and assume a hydrostatic equilibrium (approximately circular) shape; and
(c) Cleared the area around the orbit.
Unfortunately, this resulted in Pluto being demoted from planet to dwarf planet because it did not meet criterion (c).
Furthermore, IAU Resolution B5 is limited to planets in the solar system, specifically those orbiting a single star. In contrast, About 50 exoplanets They have been seen to orbit one star in a binary system (a system made up of two stars), so the IAU’s new definition, which includes exoplanets, could help establish a better framework for planets across the universe.
While IAU Resolution B5 is considered a qualitative (non-mathematical) definition of a planet, this recent study attempted to develop a more quantitative (mathematical) definition, or planetary classification, that could encompass planets and moons, both within and beyond our solar system.
To achieve this, the researchers used a set of equations consistent with criterion (c) of IAU Resolution B5 to calculate a planet’s “zone-clearing ability,” with the goal of determining the approximate size a planet would need to be for “zone-clearing ability.”
Additional equations were also used to ascertain the differences between planets and moons.So what are the most important results from this study?
“We think that planets can be classified based on properties that are easily measured: their orbital elements and masses,” Dr Margot told Universe Today.
“We found that unsupervised clustering of solar system objects according to their orbital elements and masses produces clear groupings. Clustering reveals that the moons are distinct from the planets, and that eight planets are distinct from all other objects. The existence of these groups and the gaps between the groups provide natural boundaries for the classification of planets.”
Dr. Margot continues, “We focus on the ability to clear a zone within a specified time, rather than the state of having the zone cleared. The former is robust and easily quantifiable and observable, while the latter is harder to implement and harder to quantify.”
“We propose a single removal timescale that can be applied to all stars, stellar remnants, and brown dwarfs. We propose a definition that is in line with the IAU recommendations, but also considers potential problems associated with these recommendations. We propose a simpler mass-based proposal that avoids some of these issues.”
This proposal consists of the following definitions:
What is a planet?
(a) Orbit one or more stars, brown dwarfs, or stellar remnants;
(b) has a mass greater than 1023 kg.
(c) has a smaller mass than 13 Jupiter Mass (2.5 x 1028 kg).
A satellite is a celestial body that orbits a planet.
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The company’s headquarters are in Paris, France. The IAU was founded It was founded on July 28, 1919 in Brussels, Belgium, with the mission of promoting and enhancing all aspects of astronomy, including scientific research, public outreach and worldwide education.
As of May 2024The IAU is made up of 92 countries and has 12,738 members. The IAU has held 32 General Assemblies to establish scientific protocols. A new definition of a planet was presented at the 26th General Assembly in 2006.
Examples of recent resolutions include: Protecting radio astronomy from interference and Advances in ultraviolet astronomyboth of which will be announced at the 31st General Assembly in 2021. So what steps must the IAU take to implement these three criteria for defining a planet?
“The IAU has an established process for considering and voting on proposed resolutions,” Dr Margot told Universe Today.
“In my opinion, the IAU should follow its established process and consider all reasonable proposals. Although it failed in 2024, it could be proposed again before the 2027 General Assembly, and I hope to see a more positive outcome then.”
As mentioned above, the motivation for this study stemmed from the 2006 IAU Resolution B5, which established a new definition of a planet, resulting in Pluto being demoted from planet to dwarf planet based on the new criteria.
This immediately drew skeptical reactions from the scientific community. A Message from Dr. Alan Sternis the principal investigator for the New Horizons mission, which visited Pluto in 2015. Pluto was demoted less than a year after New Horizons was launched in early 2006.
This backlash It was also seen in politics With several state governments, including California, New Mexico and Illinois, publicly denouncing the demotion, in Dr. Margot’s opinion, should Pluto be reclassified as a planet?
“Pluto is an amazing planet that deserves exploration,” Dr Margot told Universe Today.
“But classifying Pluto among the eight planets doesn’t make sense. Although there may be legitimate concerns about the scope and accuracy of the 2006 IAU’s definition of a planet, at least the outcome of the IAU resolution made sense: Pluto does not belong to the eight planets and should have been assigned to a separate class. Our work is not focused on Pluto, but on quantifying and generalizing the definition of a planet.”
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At the time of writing, NASA confirms the existence of 5,690 exoplanets And this number continues to grow steadily every day, meaning the number of exoplanets orbiting multiple stars will grow as well.
The new definition of a planet could therefore provide a better framework for identifying and characterizing exoplanets and their moons (exomoons) as we continue to explore the universe.
This recent research may help establish a framework by developing a quantitative approach to defining planets and moons in and outside our solar system, which could help improve our understanding of the universe and our place in it. Furthermore, by using mathematics to establish a new definition, it may also remove subjectivity from the definition of a planet.
“Our proposal doesn’t do anything to keep the number of planets low,” Dr Margot told Universe Today.
“Clustering analysis has nothing to do with human emotion. We would have done exactly the same thing if a group of eight planets, 12 planets or 50 planets had been generated. Eight planets were identified.
“Readers who feel frustrated that smaller objects have not been recognized as planets should take solace in the fact that these objects also merit exploration. Classification into one group or another is not an indication of scientific importance.”
How will this new definition help scientists better understand planets and exoplanets in the years and decades to come? Only time will tell. And this is why we do science.
This article is The Universe Today. read Original article.
