# How does the Sun Burn? **URL:** \ **Category:** Factual Questions\ **Created:** [September 22, 2006, 9:38am UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688 "2006-09-22T09:38:09Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![Trax](https://avatars.discourse-cdn.com/v4/letter/t/e19b73/32.png) [@Trax](https://boards.straightdope.com/u/Trax)\ **Post date:** [September 22, 2006, 9:38am UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/1 "2006-09-22T09:38:09Z")
As we all know(that may be oversaying for some) the Sun runs on Nuclear Fusion of hydrogen molecule to form helium molecule but how does it burn if there is no oxygen in space? Can someone give me the Straight Dope without resorting to Cecil? ---
**Author:** ![Nuclear\_Siafu](https://avatars.discourse-cdn.com/v4/letter/n/f04885/32.png) [@Nuclear\_Siafu](https://boards.straightdope.com/u/Nuclear_Siafu)\ **Post date:** [September 22, 2006, 9:56am UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/2 "2006-09-22T09:56:54Z")
[QUOTE=Trax] As we all know(that may be oversaying for some) the Sun runs on Nuclear Fusion of hydrogen molecule to form helium molecule but how does it burn if there is no oxygen in space? Can someone give me the Straight Dope without resorting to Cecil? [/QUOTE] You’re confusing two different reactions. We say that the Sun “burns” but what is actually happening is that the intense heat and pressure is forcing hydrogen atoms together to become helium atoms. This is a nuclear reaction. In a combustion reaction, as we usually encounter it on earth, some form of hydrocarbon and oxygen are being burned in a chemical reaction to produce water and carbon dioxide. Also, oxygen does exist in space, and even in the Sun itself, but only, IIRC, in trace ammounts in its corona, where it’s actually hottest. Outside of the Sun, most of the oxygen in space is held within ice. ---
**Author:** ![Sage\_Rat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sage_rat/32/399_2.png) [@Sage\_Rat](https://boards.straightdope.com/u/Sage_Rat)\ **Post date:** [September 22, 2006, 9:59am UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/3 "2006-09-22T09:59:33Z")
Nuclear flame… Cool! ---
**Author:** ![Trax](https://avatars.discourse-cdn.com/v4/letter/t/e19b73/32.png) [@Trax](https://boards.straightdope.com/u/Trax)\ **Post date:** [September 22, 2006, 10:09am UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/4 "2006-09-22T10:09:19Z")
@Nuke Saifu You’re saying that the Sun is not actually burning but nuclear fusion only? Huh, never knew that. Thanks. ---
**Author:** ![Malacandra](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@Malacandra](https://boards.straightdope.com/u/Malacandra)\ **Post date:** [September 22, 2006, 12:38pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/5 "2006-09-22T12:38:20Z")
[QUOTE=Trax] @Nuke Saifu You’re saying that the Sun is not actually burning but nuclear fusion only? Huh, never knew that. Thanks. [/QUOTE] Yup, if it was burning it wouldn’t last long. You get much less energy shuffling atoms around (sticking hydrogen to oxygen) than you get shuffling nuclei around (sticking protons to protons). ---
**Author:** ![Johnny\_L.A](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/johnny_l.a/32/1084_2.png) [@Johnny\_L.A](https://boards.straightdope.com/u/Johnny_L.A)\ **Post date:** [September 22, 2006, 12:47pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/6 "2006-09-22T12:47:04Z")
It burns with the fury of a thousand… No, wait a minute… ---
**Author:** ![Lemur866](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lemur866/32/434_2.png) [@Lemur866](https://boards.straightdope.com/u/Lemur866)\ **Post date:** [September 22, 2006, 4:04pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/7 "2006-09-22T16:04:56Z")
The sun burns with the fury of one sun. The sun is like a giant nuclear bomb. Gravity compresses hydrogen so tightly that it fuses into helium. This creates bucketloads of energy, so much energy that it causes the sun to expand, counteracting the force of gravity. Fusion is many orders of magnitude more energetic than any chemical reaction like burning hydrogen with oxygen. A given mass of hydrogen will have the same amount of gravity, so all stars with the same mass will fuse at the same temperature. A star that is many times more massive than the sun will have higher gravity, and so will have more fusion and will be blue-white. A star that is less massive than the sun will have less gravitational compression and will fuse more slowly and will be reddish. Blue stars will burn through all their hydrogen very quickly, so blue stars are only a few million years old. Our star is more that 5 billion years old. And red dwarf stars will last much longer. ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [September 22, 2006, 5:17pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/8 "2006-09-22T17:17:14Z")
[QUOTE=Trax] As we all know(that may be oversaying for some) the Sun runs on Nuclear Fusion of hydrogen molecule to form helium molecule but how does it burn if there is no oxygen in space? Can someone give me the Straight Dope without resorting to Cecil? [/QUOTE] Point of note: hydrogen and helium are [chemical elements](http://en.wikipedia.org/wiki/Chemical_element), not [molecules](http://en.wikipedia.org/wiki/Molecule), and in fact, helium will not react chemically with other element under normal circumstances. The “burning” of the Sun is caused by [thermonulcear fusion](http://en.wikipedia.org/wiki/Thermonuclear_fusion), which results in combining two elements together to form a single, heavier element and some additional energy in the form of electromagnetic radiation (light, heat, x-rays, radio waves, et cetera) and in some reactions, free neutrons. Stars on the main sequence at or below the mass of the Sun undergo [proton-proton chain reactions](http://en.wikipedia.org/wiki/Proton-proton_chain), a sequence of different reactions. Older or heavier stars go through the [carbon-nitrogen-oxygen cycle](http://en.wikipedia.org/wiki/CNO_cycle). Near the end of solar lifespan, nearly all stars go through the low energy [triple alpha process](http://en.wikipedia.org/wiki/Triple-alpha_process) (also called helium burning). The Sun can be conceptually considered as a “nuclear bomb” as **Lemur866** suggested, but in comparison to a thermonuclear bomb, which detonates in a few dozens of microseconds, a star goes through a very stable, if highly energetic, progression of reactions that balance the gravitational forces with the energy released by the reaction. The Sun isn’t going to suddenly blow itself apart or burn out spontaneously. Stranger ---
**Author:** ![Tapioca\_Dextrin](https://avatars.discourse-cdn.com/v4/letter/t/3d9bf3/32.png) [@Tapioca\_Dextrin](https://boards.straightdope.com/u/Tapioca_Dextrin)\ **Post date:** [September 22, 2006, 5:21pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/9 "2006-09-22T17:21:40Z")
[QUOTE=Trax] how does it burn if there is no oxygen in space? [/QUOTE] Same way as a light bulb burns? ---
**Author:** ![Stranger\_On\_A\_Train](https://avatars.discourse-cdn.com/v4/letter/s/13edae/32.png) [@Stranger\_On\_A\_Train](https://boards.straightdope.com/u/Stranger_On_A_Train)\ **Post date:** [September 22, 2006, 5:32pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/10 "2006-09-22T17:32:41Z")
[QUOTE=Tapioca Dextrin] Same way as a light bulb burns? [/QUOTE] Light bulbs “burn” via [incandescence](http://en.wikipedia.org/wiki/Incandescence) and [fluorescence](http://en.wikipedia.org/wiki/Fluorescence), powered by an elecrtric current. Both processes occur in the Sun, but they are secondary results of the fusion reactions. Stranger ---
**Author:** ![Frelling\_Tralk](https://avatars.discourse-cdn.com/v4/letter/f/ecc23a/32.png) [@Frelling\_Tralk](https://boards.straightdope.com/u/Frelling_Tralk)\ **Post date:** [September 22, 2006, 6:28pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/11 "2006-09-22T18:28:05Z")
The sun is a mass of incandescent gas A gigantic nuclear furnace Where hydrogen is built into helium At a temperature of millions of degrees ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [September 22, 2006, 6:35pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/12 "2006-09-22T18:35:44Z")
[QUOTE=Tapioca Dextrin] Same way as a light bulb burns? [/QUOTE] How many Elder Gods does it take to compress a ball of fusing gas? ---
**Author:** ![Cervaise](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/cervaise/32/16693_2.png) [@Cervaise](https://boards.straightdope.com/u/Cervaise)\ **Post date:** [September 22, 2006, 6:41pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/13 "2006-09-22T18:41:12Z")
Answer:People who ask such impertinent questions will be eaten. ---
**Author:** ![galt](https://avatars.discourse-cdn.com/v4/letter/g/35a633/32.png) [@galt](https://boards.straightdope.com/u/galt)\ **Post date:** [September 22, 2006, 6:57pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/14 "2006-09-22T18:57:37Z")
[QUOTE=Frelling Tralk] The sun is a mass of incandescent gas A gigantic nuclear furnace Where hydrogen is built into helium At a temperature of millions of degrees [/QUOTE] BTW: scientists have also found that the sun is a huge atom-smashing machine. ---
**Author:** ![Exapno\_Mapcase](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/exapno_mapcase/32/1051_2.png) [@Exapno\_Mapcase](https://boards.straightdope.com/u/Exapno_Mapcase)\ **Post date:** [September 22, 2006, 6:58pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/15 "2006-09-22T18:58:32Z")
[QUOTE=Cervaise] How many Elder Gods does it take to compress a ball of fusing gas? [/QUOTE] None. They like to leave us in the dark. [Credit to [Light Bulb Jokes](http://www.netfunny.com/rhf/jokes/88old/bulb.html).] ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [September 22, 2006, 7:07pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/16 "2006-09-22T19:07:45Z")
[QUOTE=Frelling Tralk] The sun is a mass of incandescent gas A gigantic nuclear furnace Where hydrogen is built into helium At a temperature of millions of degrees [/QUOTE] So Janet asked him for his autograph? ---
**Author:** ![Khampelf](https://avatars.discourse-cdn.com/v4/letter/k/8e7dd6/32.png) [@Khampelf](https://boards.straightdope.com/u/Khampelf)\ **Post date:** [September 22, 2006, 7:11pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/17 "2006-09-22T19:11:01Z")
[QUOTE=Frelling Tralk] The sun is a mass of incandescent gas A gigantic nuclear furnace Where hydrogen is built into helium At a temperature of millions of degrees [/QUOTE] So, you’re saying the sun might be a giant? P.S. Bryan Elkers, the hamsters ate my first post, you got the TMBG ref first, good on ya. ---
**Author:** ![JustDroppingBy](https://avatars.discourse-cdn.com/v4/letter/j/ccd318/32.png) [@JustDroppingBy](https://boards.straightdope.com/u/JustDroppingBy)\ **Post date:** [September 22, 2006, 7:22pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/18 "2006-09-22T19:22:07Z")
Does this mean that cockraoches can survive under the sun? ---
**Author:** ![Bryan\_Ekers](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/bryan_ekers/32/183_2.png) [@Bryan\_Ekers](https://boards.straightdope.com/u/Bryan_Ekers)\ **Post date:** [September 22, 2006, 8:06pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/19 "2006-09-22T20:06:17Z")
[QUOTE=The Sonoran Lizard King] P.S. Bryan Elkers, the hamsters ate my first post, you got the TMBG ref first, good on ya. [/QUOTE] Actually, mine was a ref to “Interplanet Janet” from _Schoolhouse Rock_. I know nothing about They Might Be Giants. ---
**Author:** ![Khampelf](https://avatars.discourse-cdn.com/v4/letter/k/8e7dd6/32.png) [@Khampelf](https://boards.straightdope.com/u/Khampelf)\ **Post date:** [September 22, 2006, 8:26pm UTC](https://boards.straightdope.com/t/how-does-the-sun-burn/373688/20 "2006-09-22T20:26:31Z")
[QUOTE=Bryan Ekers] Actually, mine was a ref to “Interplanet Janet” from _Schoolhouse Rock_. I know nothing about They Might Be Giants. [/QUOTE] Ooops, you’re right, looks like **galt** got \*\*Frelling Tralk’s \*\* reference, which was some lyrics from an obscure pop song from a very quirky band. I remember, now, Interplanet Janet, the galaxy girl from Schoolhouse Rock. [Next page](https://boards.straightdope.com/t/how-does-the-sun-burn/373688.md?page=2)