Over recent years astronomers have realised that chemistry plays a crucial role in controlling the evolutionary cycle where stars are formed from vast clouds of gas and dust, then age and then die either simply by cooling down or in the spectacular brilliance of an exploding star. With the help of chemists, they have created a new scientific discipline, astrochemistry, that seeks to understand the important role that chemistry has to play in our cosmos.
Astronomers use basically the same tools as chemical spectroscopists to look at stars linking spectrographs to their telescopes to measure the spectra of distant objects. Some objects, such as our Sun, produce relatively simple spectra showing the range of atoms present in the star. Other objects, such as low mass stars and "failed stars" or brown dwarfs, are so cool that their spectra is full of molecular fingerprints. However, in fact the spectra of all objects, as they grow older, become richer. We see evidence for the formation of molecules in the cooler parts of the stellar envelope. These molecules can be released from the stars into the interstellar medium only to be reduced to their constituent atoms by the harsh radiation environment to be found there.
