Observing electromagnetic radiation is a key tool in understanding the universe. Because of great discoveries in light and the electromagnetic spectrum, astronomers are able to analyze what they can see of space and also what they cannot see by studying the objects through various wavelengths. By studying the wavelengths of light energy, astronomers can discover the composition as well as the distance of objects faraway in space. Astronomers are constantly learning about the universe by studying it through all parts of the electromagnetic spectrum.

The Doppler effect does not just affect sound; it also affects how you see the light from stars. If you could see the frequency of a star increasing from where it normally should be, then you could tell that the star or object is approaching Earth. The emission or absorption lines of stars reveal certain elements of the star or object and its movement. By comparing the light of the star and its spectrum to the position of the elements that it contains, you can see a shift in the position of the wavelength.

If a star is approaching Earth, it will show a shift toward the blue end of the spectrum, called blueshift. The opposite occurs in a redshift, in which the object recedes and shows a shift toward the red end of the spectrum with the wave frequencies decreasing and the waves being farther apart. Astronomers can then measure how much the specific element signatures have moved in order to determine the speed of that movement.