Spectral Lines
Remember our light experiment a few days ago? When you use a spectroscope to split light apart, you can see a pattern of lines. Spectral lines are the pattern of colors produced when the light is split into the rainbow spectrum. Different gasses have different spectral line patterns. These spectral lines are so unique that they are like fingerprints for each element. Hydrogen's pattern is very different from Heliums, and so on.
Astronomers can use spectral lines to figure out what stars, planets and nebula are made of.
Astronomers can use spectral lines to figure out what stars, planets and nebula are made of.