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globefish23 t1_iy2zitm wrote

Reply to comment by JustinChristoph in I have finally completed the Solar System! No telescope and no equatorial mount. Just DSLRs, a fixed tripod, stacking and patience! by andrea_g_amato_art

It was recategorized into the new category 'dwarf planet' in 2006, after bigger objects (e.g. Eris, Sedna) further out in the Kuiper belt were discovered.

We would have hundreds of planets by now, and would be in the same predicament as in the 19th century with Ceres.

Ceres was initially called a planet, until the category 'asteroid' was created. Now Ceres is a dwarf planet as well.

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SoretomoOre t1_iy3uotv wrote

> We would have hundreds of planets by now, and would be in the same predicament as in the 19th century with Ceres.

I hear this on reddit a lot, but why is this a predicament? It's not illegal to have 300 planets or whatever amount. I'm all aboard the "spherical due to it's own gravity" train

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globefish23 t1_iy4i8ao wrote

>It's not illegal to have 300 planets or whatever amount.

All of these categories are pretty arbitrary in the first place, but cramming everything into one category is just cumbersome and silly.

>I'm all aboard the "spherical due to it's own gravity" train

Yes, dwarf planets fullfill this requirement (hydrostatic equilibrium). What they lack is having cleared their orbit from other objects.

Asteroids lack both of these.

It's essentially dividing celestial bodies into three groups by their mass with physically measurable thresholds.

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SoretomoOre t1_iy4o9i4 wrote

> Yes, dwarf planets fullfill this requirement (hydrostatic equilibrium). What they lack is having cleared their orbit from other objects.

I know what they decided, I just call Ceres and Pluto planets anyway 😎

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