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The Sun

Posted: Thu Jan 24, 2019 8:36 am
by CEtherington
We've had a question from John in Bolton.
He wants to know, "How do we know what the Sun is made of? "
Would any members like to help?

Re: The Sun

Posted: Thu Jan 24, 2019 9:51 am
by rwilkinson
It's by analysing sunlight using a spectrograph.
Splitting the light into a continuous spectrum, we can see lots of dark lines, each of which is due to absobtion by particular elements or molecules. These can be identified by comparing with the spectra of known substances in the lab.
It's interesting to note that the element Helium was discovered by analysis of the Sun's spectrum before it was ever found on Earth.

Prof. Jim Al-Khalili's programme all about "Light" is still available on the BBC iPlayer. About 25 minutes in he explains how spectra reveal the composition of stars. https://www.bbc.co.uk/iplayer/episode/p ... rk-1-light