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How to Determine If Stars Are Made Out of Hydrogen

Scientists are able to understand the composition of stars by analyzing their spectra with a spectroscope (also referred to as a spectrometer or spectrograph), an instrument that breaks down a beam of light into its constituent parts. These parts are seen as colors that allow observers to infer details about the light source. Spectroscopic samples show that all stars in the known universe are composed of hydrogen, along with helium and many other elements in minuscule quantities like iron, zinc and calcium. Combined with other spectra analysis, the differences and proportions of these elements allow scientists to gather information about stars even millions of light-years away.

Things You'll Need

Spectroscope
Spectra absorption interpretation chart

Instructions

- 1
  Practice using your spectroscope by aiming it at different man-made light sources and comparing their spectra. When aimed at any source of light, the tool will literally show you a rainbow through the viewfinder. Match the patterns against models of existing spectra samples (see the resources list) to help reveal what elements fuel or compose the source of light you are viewing.
- 2
  After sunset, find the brightest star in your sky. Aim the spectroscope at the star and record your observations. The intensity and variety of colored lines within the instrument will illustrate the different elements that compose the star. Notice that hydrogen will appear as intense red, blue and violet lines.
- 3
  Gradually accumulate comparisons of as many bright stars as possible. Record your findings. Multiple observations will help illustrate that all stars are composed of about 75 percent hydrogen and 20 percent helium.

Astronomy