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Since the entire solar system inherits its heavy elements from supernovae unrelated to our star, I fail to understand why, while capturing most of said system's matter, the sun only contain light elements, especially hydrogen, selecting out heavy elements found in the rest of the system, especially rocky planets like earth.

EDIT: so reading the answer offered by G. Smith it appears my initial question title is wrong, because the Sun does contain heavier elements. Not sure if I should correct it afterwards or leave it for historical reasons.

Winston
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    http://curious.astro.cornell.edu/our-solar-system/53-our-solar-system/the-sun/composition/201-does-the-sun-have-any-heavy-elements-beginner – G. Smith May 09 '19 at 16:57
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    The better question is why the earth is not made of almost entirely lighter elements like most of the rest of the universe. – Shufflepants May 09 '19 at 18:36
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    It wouldn't be very good at being a star if it were made of dark elements, for one. – 0xdd May 09 '19 at 19:06
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    As XKCD says, there's more gold in the Sun than water in the Earth's oceans. – PM 2Ring May 09 '19 at 20:23
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    @PM 2Ring: thus the color yellow. (I know that's not true.) – Winston May 09 '19 at 20:32
  • @Erin: please add a description to your link. – Winston May 10 '19 at 03:13
  • "Why Does The Sun Shine?" by TMBG lists some of the heavier elements the sun contains near the end of the song: youtube.com/watch?v=3JdWlSF195Y – Erin May 10 '19 at 03:42
  • @Shufflepants: Then we might not have been here to observe a universe where some planets deviate statistically from a mostly light element universe. Want to say: You say yourself "most" - i.e. "not all/everything". – phresnel May 10 '19 at 07:58
  • The first sentence isn't anything like the whole story. https://physics.stackexchange.com/questions/7131/what-is-the-origin-of-elements-heavier-than-iron?noredirect=1&lq=1 – ProfRob Nov 10 '23 at 14:04
  • Fuller answers at https://physics.stackexchange.com/questions/777621/why-are-stars-made-from-hydrogen-and-helium-and-not-other-elements?rq=1 – ProfRob Nov 10 '23 at 14:05

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The Sun didn’t “select out” heavy elements from the cloud. The planets selected out light elements because they don’t have enough gravity to hold on to their hydrogen and helium.

Source: http://curious.astro.cornell.edu/our-solar-system/53-our-solar-system/the-sun/composition/201-does-the-sun-have-any-heavy-elements-beginner

G. Smith
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    Thank you. That makes sense with Jupiter's ability to retain light elements as well. – Winston May 09 '19 at 17:06
  • Interesting, I never thought of it that way. So the protoplanetary disk may have had the same composition as the sun, at least for a while. So did all the planets originally have a composition similar to the gas giants, but over time the light elements left the atmosphere and were blown away by the solar wind? Where did they go? Is there a hydrogen layer at the heliopause? – Peter - Reinstate Monica May 09 '19 at 22:04
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    @PeterA.Schneider Well, not quite a hydrogen layer at the heliopause - after all, the heliosphere is an evacuated region of the interstellar medium. ISM outside of the solar system is much denser than inside. The heliopause is essentially where the pressure of the interstellar medium equals the pressure of the solar wind. The material thrown out thanks to the solar wind mixes easily with the ISM (with turbulent flow), and since it's no longer gravitationally bound to the Sun, the "leaked" hydrogen (and helium) has been dispersed over huge volumes of the galaxy in the billions of years. – Luaan May 10 '19 at 06:46