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My thoughts on the 20th anniversary of the correction of Pluto’s classification (edited by the fabulous @leebillings.bsky.social )

Once you decide that planets must orbit the sun, then it may be a matter of deciding - perhaps arbitrarily- which sub-categories of large bodies should be included in the “planet” category: rocky bodies, gas giants, ice giants, and ice/rock bodies. Many Pluto fans reject this sytematic approach.

Discovery of an object the size of Earth and the composition of Pluto may require revisiting the current taxonomy.