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.
Imagine the Universe! website hosted at
NASA's Goddard Space Flight Center has a great tutorial about
spectroscopy. The specific pages are linked below.
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