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A follow-up to my earlier question How would one navigate interstellar space? that just occurred to me; albeit on a different tack.

Sol is probably in a state of continuous flux. The change of state is probably over large timescales as compared to the life-span of the average human. If one were to compare a spectrograph of Sol over a span of, say, 10 million years, would the graph be significantly & predictably different?

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@CrazyBuddy: Would that I had dmckee, or ronmaimon, or johnrennie's expertise to come up with an answer ... sigh – Everyone Oct 28 '12 at 17:12

Each & every element has its own characteristic emission and absorption spectra (which we all know). As the star traverses its main sequence stage - the hydrogen atoms are actually getting used up to form helium atoms. As it enters the red giant phase, helium starts to fuse by the triple-alpha process.

The Hertzsprung-Russel diagram gives the relationship between temperature and luminosity (Blue, yellow, red, etc.). As we take Wien's displacement law also into account, we could conclude that the spectra (emission or absorption) of the sol varies accordingly with its temperature. Now, the sun is at some 5000 K surface temperature, which gradually decreases to something around 3000 K. And hence, the spectral shift from yellow towards red. But, that may take about 3 or 4 billion years.

Oh.. You asked for 10 million years. In that case too, the answer remains the same. It's on its own way, hanging its spectrum because its getting old..!

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