Spectroscopy is a complex art - but it can be very useful in helping scientists understand how an object like a black hole, neutron star, or active galaxy is producing light, how fast it is moving, and even of what elements it is made. A spectrum is simply a chart or a graph that shows the intensity of light being emitted over a range of eneriges. Spectra can be produced for any energy of light - from low-energy radio waves to very high-energy gamma-rays.
The Imagine the Universe! website hosted at NASA's Goddard Space Flight Center has a great tutorial about spectroscopy. The specific pages are linked below.
|Introduction to Spectroscopy|
|Making a spectrograph|
|What do spectra show us?|