Comment by jsbisviewtiful
12 hours ago
In case anyone was curious, the Moon is bigger than Pluto. Pluto's 2/3 the size of the Moon. If any dwarf planet should be upgraded to a planet, it's Eris. Eris's diameter is over 600km bigger than Pluto's.
12 hours ago
In case anyone was curious, the Moon is bigger than Pluto. Pluto's 2/3 the size of the Moon. If any dwarf planet should be upgraded to a planet, it's Eris. Eris's diameter is over 600km bigger than Pluto's.
Because the IAU does not uniquely hold claim to undeniable, universal, transcendent truth that should be received without question or doubt -- or even healthy scientific disagreement -- alternate planetary definitions exist. In at least one of them, both Pluto and the Moon are planets.
Pluto's diameter is 2376.6±1.6 km, while Eris' diameter is 2326±12 km. Perhaps you're thinking of mass instead of size?
Aye, but what does Pluto orbit, and what does the Moon orbit?
In order to be defined as a planet, an object needs to meet 3 criteria:
- Orbits a star (Pluto does and I assume that's what you were asking about)
- The object has enough mass to pull itself into a sphere (meets this criteria)
- The object has enough gravity to have cleared its nearby orbit of debris and other objects
Neither Pluto nor Eris qualify for a planet because of that last one and, like I mentioned, the Moon has more mass than Pluto and Eris. The Kuiper belt objects all have this issue, but my point was that dwarf planets are pretty small - especially compared to other objects around Sol. If you walked non-stop around the Moon it would take 91 days compared to Pluto's 62 days and Eris's 61 days.
The designation of dwarf planet is not that big of a deal imo.
Pluto orbits center of combined masses of itself and Charon, which does not lie within either of them. Also, they are both tidally locked to each other, just like Moon is tidally locked to Earth.