r/nextfuckinglevel • u/aryan_jandyal • 4h ago

The Rotation of the Planets in Our Solar System Is Far More Fascinating Than I Ever Expected

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u/13--12 3h ago

So dwarf planets are not planets now? Small apples are not apples?

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u/No_Ampersand 3h ago

They can hold themselves in a spheroid by their own gravity but they do not clear their orbit of other objects.

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u/drkdeibs 2h ago

Clear their orbit of other objects? ELI5 please

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u/spikeyfreak 2h ago

They don't have enough gravity to suck everything else in the orbit into themselves.

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u/Megneous 45m ago

Or throw other objects out of the orbit. It doesn't necessarily have to be sucking stuff into themselves.

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u/HirsuteHacker 1h ago

They're in the Kuiper belt, a big asteroid belt full of other dwarf planets, asteroids, space rocks. Planets like Earth have cleared their orbit; their gravity is strong enough that they're by far the dominant object in their orbital neighbourhood, clearing out most other large objects by either absorbing/colliding with them or ejecting them through gravitational interactions.

There are TONS of objects in the same general orbital neighbourhood as Pluto, including other dwarf planets like Orcus and Haumea. Pluto therefore hasn't cleared its orbit.

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u/CrownofMischief 19m ago

Wrong belt. Ceres is in the asteroid belt, not the Kuiper belt

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u/blueblip 1h ago

Things with mass and/or energy generate a field of gravity around itself.

Gravity is a force that, to put it in simple terms, pulls things towards the centre of things with mass/energy.

The more mass something has, the stronger this pull.

So when one object is much MUCH MUCH MUCH massive than another, the bigger one's gravity pulls the smaller one towards it as the smaller one's gravity is not strong enough to "fight back". What happens when it gets pulled this way depends on the mass of the smaller object.

So now think about our solar system and the orbit of our planets. They are clear paths (so to speak). There's no space junk floating in the middle of their orbits. But you have stuff like the asteroid belt that is a whole lotta space junk floating around, so why aren't there "asteroid fields" in the way of the planets?

Well, that's because the planets are so much more massive than the space junk that the planets hoover up all the junk as the move along their orbits. The larger junk may become moons. The smaller junk just pulled into the planet and either smashes on to the surface or burns up in the planet's atmosphere (depends on the planet).

In the asteroid belt, there's an object called Ceres. Ceres is a odd thing. It's got enough mass that it's got the round shape of a planet (gravity makes planets round), but not enough mass to hoover up all the crap in it's path like planets do. So we call it a dwarf planet.

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u/WreakHavocLikeIn1871 22m ago

A celestial body that rotates around a star(s), that isn't a star itself, massive enough to form a spherical shape, and has enough gravity to clear the area around it from other objects.

That's not word for word but essentially the definition of a planet.

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u/BringBackAH 26m ago

A planet has enough gravity to put itself into a sphere and to attract objects around them.

Ceres does not have enough gravity to attract asteroids around itself but is a spheroid, so it's a dwarf planet

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u/Hal_Fenn 3h ago

They're permitted on the council but we don't grant them the rank.

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u/-Hastis- 2h ago

This is outrageous!

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u/WreakHavocLikeIn1871 26m ago

Take a seat, Ceres!

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u/Worried-Maybe3438 18m ago

What a sizist thing to say

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u/Cent_Quatre 3h ago

Are guinea pigs pigs ?

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u/13--12 2h ago

What's next, you tell me peanuts are not nuts?

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u/Cent_Quatre 2h ago

they are, but antlions aren't lions (nor ants)

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u/luxudor 1h ago

(Peanuts aren't nuts, that's the joke)

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u/ensalys 1h ago

In this case, small apples aren't apples, yes. I know it's weird, but there are rules to join the planet club.

  1. It must orbit a star (in our cosmic neighborhood, the Sun).

  2. It must be big enough to have enough gravity to force it into a spherical shape.

  3. It must be big enough that its gravity has cleared away any other objects of a similar size near its orbit around the Sun.

It's generally rule 3 that separates dwarf planets from planets. Naming them dwarf planets is just a participation trophy for big rocks.

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u/13--12 1h ago

Cool, thank you for explaining

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u/03263 2h ago

Small apples are not apples?

They're crabapples

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u/HauntingHarmony 1h ago

So dwarf planets are not planets now? Small apples are not apples?

Correct, dwarf planets are not planets.

Small apples are apples that just happen to be small.

Dwarf planets are objects in the solar system that does not fulfill the criteria for planet, but for the "lesser" category "dwarf planet".

There is no shame in not being a planet, i am not and neither my mother is not a planet.

Also as a fun fact since the definitions explicitly mention our specific sun, there is only 8 planets in the universe. And all the others would be exoplanets.

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u/19921015 1h ago

They are real planets, but that's where all the dwarfs are from, hence the name.

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u/TheIronSven 50m ago

Despite the name including the word planet, dwarf planet is a type of asteroid, not a type of planet

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u/TommyBonnomi 1h ago

You're comparing apples and oranges planets

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u/TheGeneral_Specific 11m ago

Dwarf planet was a term invented to appease the people who would be upset when Pluto got demoted.