To people on earth, the millions of stars in the night sky look like white dots. But all objects in the universe emit, absorb, and reflect the electromagnetic radiation in different ways.

Astronomers can study exactly how the objects emit, absorb, and reflect electromagnetic radiation to learn more about them.

• They can use a spectrograph to break up the electromagnetic radiation into component colors.
• This is the same thing that happens in nature when raindrops act as prisms for sunlight, creating a rainbow, which is a light spectrum.
  • Stars also have light spectra.

Review

• Q: What is the definition of spectrograph?
• A: A tool that astronomers can use to see the light spectrum of a star