absorption lines
Kirchoff’s 3rd situation: a cool gas infront of a heated solid or liquid gives absorption lines
- the wavelengths of the lines are the same as would be seen in emission from a heated gas
- the atoms, instead of decaying, are being excited to higher energy orbits, removing photons from the beam
- In fact, the spectrum of the solar photosphere shows absorption lines
- the wavelengths of the lines identify the atoms present
- the strengths of the lines indicate the abundances