Scientists Re-Establish Pluto As A Real Planet

First Posted: Mar 20, 2017 05:04 AM EDT

A team of planetary scientists drafted a definition of a "planet" and its justification that will be presented at the Lunar and Planetary Science Conference in Texas this week. They are re-establishing Pluto's status into a "planet" as well as Jupiter's moon Europa and over 100 other celestial bodies in the solar system.

The paper was led by authors Kirby Runyon, a scientist from Johns Hopkins University, Michael Summers of George Mason University in Fairfax, Virginia, Tod Lauer of the National Optical Astronomy Observatory in Tucson, Arizona, S. Alan and Kelsi Singer of the Southwest Research Institute and Will Grundy of the Lowell Observatory in Arizona. They are all members of the New Horizons mission to Pluto, which is managed for NASA by the Johns Hopkins University Applied Physics Laboratory.

Runyon claims that Pluto is a planet based on the definition and justification of what a real planet they proposed. They define the planet as a sub-stellar mass body that has never gone through a nuclear fusion. The object also has sufficient gravitational mass to keep its round shape although it expands at the equator due to a three-way squeeze of forces generated by its gravity and the impact of the Sun and close-range bigger planet.

The new definition is more helpful to planetary scientists and is more useful than the IAU's astronomical definition. It is also adopted now by the Planet Science Research Discoveries, which is an educational website established by the scientists from the University of Hawaii at Manoa, according to

The International Astronomical Union declassified Pluto as non-planet because Pluto had not cleared the neighborhood around its orbit. This makes the nine planets of the Solar System to eight. Based on IAU definition, a planet is recognized as such as having cleared the neighborhood around its orbit, has enough mass for its self-gravity and is in orbit around the Sun, according to Conservation. 

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