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By Andrew Follett
Astronomers want to reclassify Pluto as a planet again, according to the blog Universe Today.
In fact, astronomers want to redefine the planet’s classification based on the geophysics of an orbiting body, not just whether or not it orbits the sun.
If successful, the solar system would have more than 100 planets, including many bodies we currently call moons. The effort is being led by Kirby Runyon, a doctoral student at Johns Hopkins University.
Runyon’s team wants to formally define a planet as “a sub-stellar mass body that has never undergone nuclear fusion and that has enough gravitation to be round due to hydrostatic equilibrium regardless of its orbital parameters.” The team will present their findings at the Lunar and Planetary Science Conference in Texas from March 20 to 24.
This definition can be paraphrased for school children as a “round objects in space that are smaller than stars.”
Pluto was defined as a planet until 2006 when the International Astronomical Union officially downgraded its status to “dwarf planet.”
Astronomy studies claim that current definitions of what constitutes a planet are technically flawed as they only say that planets orbiting stars “count.” That ignores numerous “rogue planets.” Researchers also said the current definition would unfairly exclude a hypothetical Earth-sized object in the outer solar system’s Kuiper Belt.
This new definition would be tailored to planetary scientists, not astronomers. Earth’s moon was considered a planet by ancient astronomers, and has several unusual features that set it apart from other moons in the solar system. It is very large relative to the body it orbits and isn’t in the equatorial plane of its parent planet.
There are currently four recognized dwarf planets in the solar system other than Pluto, but NASA suspects there could be over 100 such objects that haven’t yet been discovered.