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xkcd #3063: Planet Definitions (xkcd.com)

submitted 1 week ago by [email protected] to c/[email protected]

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Under the 'has cleared its orbital neighborhood' and 'fuses hydrogen into helium' definitions, thanks to human activities Earth technically no longer qualifies as a planet but DOES count as a star.

https://explainxkcd.com/3063/

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[–] [email protected] 1 points 1 week ago (11 children)

If you pick a random Earth-sized lump of the Sun as a potential planet, and swap its place with Earth, Earth would quickly get mixed in with the rest of the Sun and stop being a distinct entity, so be very silly to still call a planet,

Why? Everything about Earth is still the same, skies, oceans, etc. Only difference is that it's crowded in by other bodies now.

Trying to scientifically judge if a body is a planet by something external to it, if it's being crowded in our not, it's not logical, and doesn't change the body itself.

What does a body clearing is orbit or not have anything to do with the body itself?

Location makes some difference to whether or not something’s a planet.

Only because a very few human beings astronomers illogically/arbitrarily decided that's so. The reality on the ground for the body is that its still Earth, the planet we live on.

Planetary Scientists should be deciding the rules, and not solely Astronomers.

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[–] [email protected] 5 points 1 week ago (10 children)

I personally don't think they can be counted as skies and oceans etc. anymore when they're being mixed in with multi-thousand-degree hydrogen/helium plasma. On a cosmological timescale, the Earth is converted to just more plasma in an instant. The reality on the ground of the body is that the ground's gone and everything living there is gone and so's the mantle under the ground. Things are defined partially by their interactions with their surroundings and the state they're currently in, not how they used to be. Theia is not a planet, even if the theory where it once was turns out to be right. It stopped being a planet when it collided with the Earth, disintegrated, and re-accreted into parts of the Earth and the Moon.

[–] [email protected] 1 points 1 week ago* (last edited 1 week ago) (9 children)

I personally don’t think they can be counted as skies and oceans etc. anymore when they’re being mixed in with multi-thousand-degree hydrogen/helium plasma.

So Mars never had oceans? Or an atmosphere?

So Saturn's moon Titan doesn't have lakes? Or an atmosphere?

What happens if a body is found in the Oort Cloud that has an internal heat source so that it has a internal ocean like Europa? It's it still not a planet because the space around it is busy?

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[–] [email protected] 2 points 1 week ago (1 children)

Your original idea only holds if it's still valid to claim Mars still has oceans, even though they're all gone. When things stop existing, it changes their properties.

[–] [email protected] 1 points 1 week ago* (last edited 1 week ago) (1 children)

Your original idea only holds if it’s still valid to claim Mars still has oceans, even though they’re all gone. When things stop existing, it changes their properties.

My latest point was to counter your latest point that things like bodies of water or atmosphere should not be considered criteria for identifying a planet or not,

Also, Mars may still have water, under the surface.

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[–] [email protected] 2 points 1 week ago (1 children)

That wasn't a point I made. You said the Earth's skies and oceans would be the same after the hypothetical Earth swaps places with an Earth-sized lump of the Sun event, and I pointed out that they'd be destroyed within seconds. That was kind of separate to the original poorly-thought-through suggestion you made about planet location swaps, and was a second poorly-thought-through claim.

[–] [email protected] 1 points 1 week ago (1 children)

You said the Earth’s skies and oceans would be the same

No, that's not what I was saying, at all.

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[–] [email protected] 1 points 1 week ago

Everything about Earth is still the same, skies, oceans, etc. Only difference is that it’s crowded in by other bodies now.

Is pretty clearly saying the skies and oceans would be the same after the Earth's been swapped with part of the Sun.

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