What can we learn about stars?
Light
is split into spectral colours, corresponding to wavelength.
Red light has long wavelengths, blue light has short wavelengths.
Spectra
- from hot objects are continuous, like a rainbow
- atoms only emit light of specific colours, revealing their
fingerprints as a line spectrum
- atoms in front of a hot object absorb light at these colours, giving an
absorption spectrum
Stellar spectra
are predominantly absorption spectra
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