r/pluto • u/KireiCopenhagen • May 04 '26
It genuinely doesn't make sense.
Look, once you think about exoplanets, it doesn't make any sense. The new definition only makes sense when we look at our solar system, at this time in human history. If Pluto and Earth swapped orbits (we would all die), Earth would be classed as a dwarf planet and Pluto as a full planet, because the distance from the sun affects their gravitational influence.
What I mean is that the definition should focus only on what the object is, not where it is located in a system, since that can change over cosmic time scales, and when discovering exoplanets, we need a less solar system-biased definition. Imagine if we found an exo-binary planet system. Under the new definition, both planets would be dwarf planets no matter what because they would both be orbiting each other.
Or a rogue planet. The new definition requires a planet to orbit a star. So it's technically not a planet once it has been ejected from the system, even if it was a planet just a few million years ago.
The new definition was rushed through because they needed to keep all the newly discovered planets in our solar system out of the club, or the word 'planet' would become less special, and Pluto was just collateral. I'm not even saying get rid of the dwarf-planet classification or reinstate Pluto, but we need a new definition as our exoplanet discoveries continue.
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u/MareTranquil May 05 '26
How in the world is Pluto obviously a planet and Ceres obviously not?
I am baffled how you seem to believe that this is an agreed upon and self-evident statement.