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GetsGold t1_j3kc4mu wrote

Reply to comment by irbinator in TIL Pluto hasn't completed an orbit around the sun since its discovery. Pluto's orbit takes about 248 years, and Pluto was discovered in 1930. by irbinator

He discovered Eris, which was more massive than Pluto.

Ceres was a planet that was discovered between Earth and Mars and Jupiter in 1801. Around 50 years later after several more planets were discovered in that region they started referring to them as asteroids instead.

That's similar to what happened with Pluto. At first it seemed unique in its part of the Solar System, but by the 90's we started discovering many other objects in that region, another belt. So with Eris they decided to treat it like the asteroid belt and stop calling its members planets.

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irbinator OP t1_j3kfgei wrote

Ah, you’re completely right. Thanks! I always mix up Ceres and Eris. I’ll update my comment now.

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