• Question: why do stars burn gas?

    Asked by applepie7 to Amy, Grant, Martin, Shawn, Usman on 19 Mar 2013.
    • Photo: Grant Kennedy

      Grant Kennedy answered on 19 Mar 2013:

      The conditions at the centre of most stars are so hot and dense that Hydrogen is turned into Helium by nuclear fusion. So really the reason that they burn gas is that they are big enough that the conditions are right in the centre.

      There are actually stars that aren’t big enough to burn gas, we call them brown dwarfs.
      g

    • Photo: Martin Archer

      Martin Archer answered on 19 Mar 2013:

      Stars don’t burn gas in the conventional sense but undergo nuclear fusion. The Sun and stars are made primarily of Hydrogen in a state called a plasma, which is a gas so hot that it fully ionises. The Hydrogen nuclei, which are simply protons, are so hot that the they have enough energy to overcome the electric force that tries to keep them apart (remember protons are positively charged). This means that protons can fuse together forming Helium nuclei in a nuclear reaction which gives out loads of energy, far more than chemical reactions can. So that’s where and why the energy from stars comes from.

    • Photo: Amy Tyndall

      Amy Tyndall answered on 21 Mar 2013:

      Even my favourite film can teach you about astronomy! 😀

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