As a result of the Big Bang, the Universe is expanding. This causes spectral lines which would normally appear in the ultraviolet and visible part of the spectrum to be doppler shifted into the infrared for very distant objects. This means that infrared spectroscopy is a valuable tool for understanding conditions in the early Universe. An example of this can be seen in the spectrum of the most distant quasar currently known . The doppler shift of spectral lines also allows astronomers to detect and measure the velocity of planets around stars, stars around stars, expanding stellar atmospheres, outflows from star forming regions, rotating rings in galaxies, rotating spiral arms, supernova explosions, and shock waves from colliding galaxies.
Infrared light is radiated from any object with a temperature.
Even objects which are too cool to be detected optically can be studied in the infrared. It was detected in very cold and thin molecular clouds by its infrared absorption lines. The discovery of this molecule and the measurement of its abundance will lead to a better estimate of the abundance of hydrocarbons in space. To see some of the molecules which have already been discovered in interstellar space click here . Infrared spectral studies are providing stunning information about the role of interstellar molecules in the formation of stars, planets and possibly even life.