For most people, the closest they get to spectroscopy – the study of the spectrum – is looking at a pretty rainbow. For astronomers, the pretty rainbow produced by stretching out the light of celestial objects is more than just something nice to look at, it contains information on materials in and around the object. Temperature, chemical composition, velocity. It can differentiate between various types of Supernovae. If the spectrum is extended so that as well as visible light, frequencies the eye cannot see are included – gamma rays, x-rays, infrared, microwave, submilimetre, radio – then the information available grows too.
Two American universities of note have websites introducing spectral studies, to help people get a grip on what is happening. Caltech’s website, known as the Cool Universe, includes an introduction to the spectrum concentrating on infrared information (images, spectra and the like). Harvard’s take, known as the Virtual Spectrometer, is slanted towards teaching all about the velocity induced Doppler shift and measuring the motion of galaxies using it. Both have games and different ways of introducing the concept of spectral lines – fingerprints of chemicals that can be found in a well studied spectrum.