When light goes through a prism, it separates into many colors. This band of colors is called a spectrum. A rainbow is an example of a spectrum: red, orange, yellow, green, blue, violet.
The interior of a star produces a continuous spectrum of light, like a rainbow. Cooler gases in the outer layers of the star absorb certain wavelengths of light, causing dark lines to appear in the spectrum.
The resulting absorption spectrum can tell astronomers a great deal about the star. It's like a finger print or bar code that tells information about the star's color, composition, and surface temperature.
Open the Star Spectra Gizmo.
Turn on Show labels. Select star 1 to see its absorption spectrum.
How many lines do you see in the spectrum? __________
Drag the neutral Hydrogen spectrum next to the Star spectrum so that the edges line up. Do some of the lines on the two spectra match up? __________
Drag the neutral Helium spectrum next to the Star spectrum. Do some lines match? __________
Try out the other available spectra. Make sure to check both the neutral spectra and ionic spectra. Do any others have lines that match? __________