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Jorgen_Pakieto t1_j56wtz7 wrote

No because it is smaller than the earths moon

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rosen380 t1_j56xlnc wrote

That isn't part of the reason it was "downgraded" to dwarf planet though... per the IAU these are the requirements:

  1. It is in orbit around the Sun.
  2. It has sufficient mass to assume hydrostatic equilibrium (a nearly round shape).
  3. It has “cleared the neighborhood” around its orbit.

Pluto meets the first two, just not the third.

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rickny0 t1_j56y7nr wrote

IMO Pluto lost its status because astronomers kept discovering more Pluto-sized objects orbiting the sun and they didn’t want to add a bunch of new planets. (Eris · Ceres · Haumea · Makemake)

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alanz01 t1_j56yxqx wrote

I would totally be on board with having more planets. Those darn astronomers!

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Dahnlor t1_j5716jp wrote

Nitpick: Ceres is in the Asteroid Belt and was discovered in 1801. Its discovery was not unlike that of Pluto, and it was considered to be a planet until after several other asteroids were discovered.

Pluto's discovery and eventual recategorization was pretty much the same situation, except that every new Kuiper Belt Object wasn't being counted as another new planet. When Eris was discovered, which is larger than Pluto, it forced the IAU's hand in creating an actual definition for "planet".

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