This is an observational exercise where I have to find several different light sources and observe their spectra through a diffraction grating, then record my observations. I need two sources of each (i.e. continuous, emission, absorption). Continuous and emission are fairly easy, but for the life of me I can't think what I could observe that would produce an absorption spectrum. I know that absorption spectra come about when there is an absorbing material like cool gas in front of a black body but I don't really know how I could find something like that. I thought maybe if I looked at a light source from far away in cold weather that might do it, but I still didn't see an absorption spectrum. Any help or hints would be much appreciated!