• Kairos@lemmy.today
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    18 小时前

    All energy comes from the sun except for geothermal which comes from the Earth’s rotational momentum which might as well be the sun because it wouldn’t rotate without something to orbit around.

    • gandalf_der_13te@feddit.org
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      5 小时前

      btw geothermal does not come from the earth’s rotation. it mostly comes from nuclear decay of heavy isotopes in the earth’s interior and the enormous heat capacity of the earth’s interior, which means it’s still warm from the friction heat from when the planet first formed. in other words it’s there since the Earth formed, independent of the sun.

      also there’s another (practically accessible) form of energy that comes neither from geothermal nor from the sun: you can pull energy out of the tidal movement that comes from the moon’s changing gravity field as it orbits around our planet. i think that one’s not really being used though because the only way to really utilize it is to build dams across havens and important shipping routes and that interferes with trade, which is considered the more economically valuable activity from the two.

    • cecilkorik@piefed.ca
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      18 小时前

      Technically nuclear came from a different star. The sun won’t create those kinds of heavier elements until it burns through its hydrogen and helium fuel to start fusing its way up to lead, and I don’t think it’s massive enough to actually reach the kind of supernova collapse required to smash lesser elements together into heavier elements than that in any significant amount. So technically, fission is the only the form of energy that isn’t based on solar. It’s just the still-cooling-embers leftover from someone else’s dying star, a whole bunch of billions of years ago. I guess you could say the sun’s gravity at least attracted it all into this general vicinity though, at least until the Earth’s own gravity started pulling its own weight.

        • gandalf_der_13te@feddit.org
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          5 小时前

          well actually there’s renewable energy on the cosmological scale (look up E. Harris - Mining Energy In An Expanding Universe), at least theoretically. nobody’s ever practically utilized it (afaik).

      • TehWorld@lemmy.world
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        17 小时前

        TIL - according to one source 80% of the geothermal energy comes from radiation and the remaining 20% is from the sun.

      • Rakonat@lemmy.world
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        10 小时前

        Yes but no. The sun didn’t form the Earth. The Earth and the sun both formed from a primordial star. You don’t hear much talk about the star that actually birthed us, because theres very little we can say for certain about it. We can’t even say for certain if Sol (the sun) is a second or third generation star because we only have vague notions about if the star that produced all the elements that aren’t hydrogen in the solar system was long lived or went nova in under a billion years.

      • betanumerus@lemmy.ca
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        15 小时前

        The molten core is hot because a whole lot of rocks crashed into each other. Also, nuclear decay.

        • NotMyOldRedditName@lemmy.world
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          14 小时前

          Well… those are remnants of a supernova aren’t they? So the velocities to have meaningful impacts came from a sun?

          Definitely not what I was thinking or trying to say though, and not our sun, but kinda still all the energy comes from at least, a sun.

          • betanumerus@lemmy.ca
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            10 小时前

            Decaying nuclei is from supernova, but the rocks that formed the solar system and Earth? I’m not sure they can pinpoint an origin. I think atoms of a rock have different origins and at some point, they combined to form the rock, so that’s also an origin. To be verified.