Astronomers use the terms "red shifted" and "blue shifted" to describe how light changes as an object moves closer to or away from an observer. The Doppler effect affects light waves the same way it affects sound waves. As an object in space moves farther away from the observer, the light it gives off is shifted to the red end of the visible light spectrum because its wavelengths are longer due to the doppler effect. If an object moves closer to the observer, the light it gives off is shifted to the blue end of the visible light spectrum because its wavelengths are shorter. Astronomers have been able to use this to measure the expansion of the universe. Red shift and blue shift can apply to all of the electromagnetic spectrum. Red shift can