Just like humans, death starts at the point of birth.
When the sun ignited and drove away the dust and debris around it, it wass about 70% as luminous as it is today. Stellar evolution theory now (in the last ten years) accounts for that; main sequence stars grow in luminosity over the main sequence lives. The sun's mass has it growing at the rate of 10% additional luminosity every 1.1 billion years. In another 1-2 billion years the luminosity will grow to the point where wholesale vaporization of the oceans will begin, and that will mark the end for us here (there are other terminations before then not associated with the sun, however). In about 5 billion years the core will have been exhausted of hydrogen and will begin to collapse. It will become hotter, perhaps hot enough to fuse helium, but the additional heat will cause the outer layers to expand the sun into a red giant and move it off the main sequence. From there it will eventually drive those loose outer layers off into space, forming a planetary nebula, and the remaining core will become a white dwarf, and slowly cool to a cinder of cold helium.
When the sun ignited and drove away the dust and debris around it, it wass about 70% as luminous as it is today. Stellar evolution theory now (in the last ten years) accounts for that; main sequence stars grow in luminosity over the main sequence lives. The sun's mass has it growing at the rate of 10% additional luminosity every 1.1 billion years. In another 1-2 billion years the luminosity will grow to the point where wholesale vaporization of the oceans will begin, and that will mark the end for us here (there are other terminations before then not associated with the sun, however). In about 5 billion years the core will have been exhausted of hydrogen and will begin to collapse. It will become hotter, perhaps hot enough to fuse helium, but the additional heat will cause the outer layers to expand the sun into a red giant and move it off the main sequence. From there it will eventually drive those loose outer layers off into space, forming a planetary nebula, and the remaining core will become a white dwarf, and slowly cool to a cinder of cold helium.
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It will last as it is now for about 4.5 to 5 billion years. Then it will enter a red giant phase for a few million to a hundred million years and then turn into a white dwarf and dwindle out of existence for the next few hundred billion years
4.5 billion main sequence
10 million red giant
100 billion white dwarf
4.5 billion main sequence
10 million red giant
100 billion white dwarf
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It's happening now ... and will take another 6 billion years or so before it expends all its hydrogen.
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It will probably die in 5 billion years.
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It's only a matter of time O_O
... About 6 billion years.
... About 6 billion years.