Teacher resources and professional development across the curriculum
Teacher professional development and classroom resources across the curriculum
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When light passes through a prism, it separates into the colors
that make it up. White light changes to a swath of colors. This
rainbow is called a spectrum. You can make spectra (the plural of
spectrum) in many ways: with a prism, with drops of water (as in a
real rainbow), or with gratings (like in the glasses you can get).
Scientists build special instruments to separate light, usually with
gratings. These instruments are called spectrographs. When astronomers pass the light of a star through a spectrograph,
they get a spectrum of the star. The spectrum looks like a regular rainbow of
colors—except that there are dark lines in it. Here is a spectrum of
our sun: What's going on? It turns out that each element absorbs light of a particular
frequency—a particular color. If that element is in the cool
atmosphere of the star, those atoms will absorb the light at that
color and produce the line. Each element has a specific
"signature"—a specific set of line. On the next page, you will figure out the composition of some stars
made specifically for this study. Go!
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