The Sun’s Energy Doesn’t Come From Fusing Hydrogen Into Helium (Mostly)
“It might surprise you to learn that hydrogen-fusing-into-helium makes up less than half of all nuclear reactions in our Sun, and that it’s also responsible for less than half of the energy that the Sun eventually outputs. There are strange, unearthly phenomena along the way: the diproton that usually just decays back to the original protons that made it, positrons spontaneously emitted from unstable nuclei, and in a small (but important) percentage of these reactions, a rare mass-8 nucleus, something you’ll never find naturally occurring here on Earth. But that’s the nuclear physics of where the Sun gets its energy from, and it’s so much richer than the simple fusion of hydrogen into helium!”
Ask anyone where the Sun (or any star) gets its energy from, and most people will correctly answer “nuclear fusion.” But if you ask what’s getting fused, most people – including most scientists – will tell you that the Sun fuses hydrogen into helium, and that’s what powers it. It’s true that the Sun uses hydrogen as its initial fuel, and that helium-4 is indeed the end product, but the individual reactions that take place to turn hydrogen into helium are surprisingly diverse and intricate. There are actually four major reactions that take place in the sun: fusing two protons into deuterium, fusing deuterium and a proton into helium-3, fusing two helium-3 nuclei into helium-4, and fusing helium-3 and helium-4 in a chain reaction to produce two helium-4 nuclei. Note that only one of those reactions actually turns hydrogen into helium, and that’s not what makes up either the majority of reactions or the majority of the Sun’s energy!
© 2011–2023 Powered by Tumblr