why cant the sun keep shining for ever?

why cant the sun keep shining for ever and how much longer do scientists think the sun will continue to shine?

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  • Anonymous
    8 years ago
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    The Sun is a large fusion reactor that converts hydrogen into helium, releasing tremendous amounts of energy. The outflow of energy from the central regions of the Sun provides the pressure necessary to keep it from collapsing under its own weight. As the Sun ages, nuclear reactions outside the core cause the dying star to expand outward in the "red giant" phase before it begins its inevitable collapse. Eventually the Sun will collapse and turn into a white dwarf star.

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  • 8 years ago

    The Sun emits energy (light, heat, UV rays, etc.). To do that it uses up a fuel through a process.

    The process is fusion (not fission) whereby four atoms of hydrogen (four protons) are "fused together" to produce one atom of helium (2 protons + 2 neutons), two positrons (also known as anti-electrons) and two neutrinos, plus some energy.

    The energy comes from the fact that all this (helium + positrons + neutrino) has a bit less mass than four hydrogen atoms.

    E = m c^2

    The energy (E) comes from some of the mass (m) being changed into energy (the c is a constant to make the units come out).

    The Sun uses up over four million tonnes per second. It cannot last forever.

    The bigger problem is that the protons fuse because they collide (the core of the Sun is very hot and the pressure is extreme, it is therefore "easy" for protons to collide at great speed, and fuse) and these collisons are random. Each time an helium atom is produced, it just sits there and gets in the way.

    In roughly 5,000,000,000 years (five billions) the Sun will still be 90% hydrogen, but there will be enough helium to interfere with the random collisions, and that will be enough to "clog the furnace".

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  • 8 years ago

    The sun shines due to nuclear fusion. As big as the sun is, it only has a limited supply of hydrogen to fuse into helium. At some point, the sun will run out of hydrogen and it will start to make heavier elements and swell into a red giant. After this, it will have done most of what it can do and shrink into a white dwarf

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  • 8 years ago

    Like all things giving off energy, the sun requires fuel. It uses hydrogen - and due to the sun's gravity, immense heat and pressure in it's core fuses hydrogen into helium.

    At some point, there will be too little hydrogen left to continue the reaction, and that will be the beginning of the sun's death - but, we still have about 4 billion years before that happens...

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  • 8 years ago

    The sun 'shines' because it is releasing light. This light is generated by nuclear fusion, which primarily occurs in the sun's core. It fuses hydrogen atoms together to make helium-2, which is fused with hydrogen and helium-2 to make helium 3 and 4. These are fused together later on, but eventually the sun runs out of hydrogen. It starts burning heavier elements, but when it can not react enough with heavier elements, it will explode and become a white dwarf.

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  • 8 years ago

    our sun is 5 billion years old and will shine for 5 billion more. it shines due to something called hydrogen fission which produces a lot of energy and as a result a lot of light and heat energy is given off. when the sun runs out of fuel it will stop shining.

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  • Tom
    Lv 5
    8 years ago
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