Justice for Pluto


For 12 years, Pluto, small and mighty, has drifted about the universe, living its life as a dwarf planet just because science said so. It was back in 2006 that the International Astronomical Union deigned to reclassify Pluto—which was widely known as a straight-up planet for much of its existence—as a “dwarf planet.” But now there’s a group of scientists who, believe it or not, believe science is wrong.

CNN reports:

The research, published in the scientific journal Icarus, says Pluto never should have been downgraded from a planet to a dwarf planet 12 years ago. Why? Because, the authors say, the rationale behind the decision wasn’t valid.

The issue has to do with Pluto’s size and orbit:

The IAU defined a planet as a celestial body that orbits the sun, is round or nearly round and “clears the neighborhood” around its orbit.
It’s that last part that’s currently in dispute. The IAU said Pluto was just too small to clear the neighborhood, or knock other space rocks out of its path as it orbits the sun. And so, the astronomical union demoted Pluto to dwarf planet status.

This past weekend, I watched hours of television about planets and exo-planets (there’s a carbon-based planet that’s essentially a giant diamond in space), so I feel uniquely qualified to comment on this.

I believe Pluto is a planet.

And so does Philip Metzger, the lead author of this study and a planetary scientist for the University of Central Florida. “The IAU definition would say that the fundamental object of planetary science, the planet, is supposed to be defined on the basis of a concept that nobody uses in their research,” Metzger said in a statement. Via CNN:

Metzger goes a step further, saying a planet should be classified based on if it’s big enough that its gravity allows it to become a spherical shape, according to the school’s statement. “And that’s not just an arbitrary definition,” he said. “It turns out this is an important milestone in the evolution of a planetary body, because apparently when it happens, it initiates active geology in the body.”


Metzger said the only planet more complex than Pluto is Earth. And we’ve learned so much more about Pluto after NASA’s New Horizons spacecraft flew past it in 2015. Thanks to New Horizons, we now know that Pluto has dunes made of solid methane ice, mountain peaks covered in methane snow and, possibly, an icy, underwater ocean.

Pluto is so rich and complex. All we have at the moment is debate around the issue of its status, until someone steps up and proposes to re-planetize Pluto. Will it be me?

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