Our Sun contains helium. We know this because there are black lines in the spectrum of the light from the sun where helium has absorbed light. These lines for he absorbtion spectrum for helium.
When we look at the spectrum of a distant star, we still see an absorption spectrum. However the pattern of lines has moved towards the red end of the spectrum, as you can see below.
Astronomers have found that the further from us a star is, the more its light is red-shifted. This tells us that galaxys are mving away from us, and that the further away a galazy is, the faster its moving away. Evidence for a generally expanding universe.
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