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Pluto Demoted Day, 13 years later — do we want our former ninth planet back?
No one wants to get rejected, whether you’re a person or a planet.
Pluto never actually got kicked out of the solar system, but on this day in 2006, the International Astronomical Union decided to take away its planet status. It has officially been a dwarf planet ever since. Space geeks (and even many astronomers) thought this was so harsh that today is officially Pluto Demoted Day. But why demote a celestial object that had been considered a planet for so long–and re-wire everyone’s brain to remember there are only eight “real” planets?
Maybe whoever decided this would think twice if Pluto really was a psychedelic orb like the trippy NASA image above that was colored to distinguish its regions.
When the IAU came up with a new definition for planets, Pluto just didn’t make it. Its planetary status was first questioned in 1992, when a group of astronomers discovered objects beyond Neptune that were more massive than what was then still the ninth planet. With more and more trans-Neptunian objects emerging from the darkness of space, the astronomical community started to question what Pluto really was, and the IAU eventually redefined planets.
At least for now, the IAU says 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 (c) has cleared the neighborhood around its orbit.”
Unfortunately, Pluto doesn't meet those criteria. It was demoted from planet to dwarf planet. When the IAU was deciding on the new definition of a planet, it also created a class of objects known as dwarf planets, which also included Ceres and Eris. These trans-Neptunian objects have even been classified by the IAU as plutoids, but some still feel that doesn't make up for downgrading what had been considered a planet for 76 years before that.
So what is the Twitterverse saying about Pluto 13 years after the decision that will live in infamy?
Like, even Bridenstine said it. Come on.
When a kids' book about this exists, you know it's serious.
Stuffed planets make it even more serious.
Oh, and this.
Just one more thing ...