Though many people may hear “Doppler Radar” as tool for tracking weather systems, it is used for much more and has roots in science dating back generations. The Doppler Effect, as it is known, is also an important aspect of the astronomical study of light. It is also important in the study of the weather and even sound. The shifting of frequencies of light and sound can determine much about their properties and their sources. Astronomers study “blueshifting” and “redshifting” because of the Doppler Effect to understand how stars and galaxies are moving throughout the universe. Meteorologists study the Doppler Effect to determine potentially life-saving information about critical developments in storms.

Zone in on the facts on the Doppler Effect:

1. The Doppler Effect is the shifting of frequencies of sound as they approach or move away from an observer.

2. The Doppler Effect also applies to frequencies of radio and light and is used in meteorology and astronomy.

3. Austrian physicist Christian Doppler (1803-1853) discovered the Doppler Effect in 1842.

4. The Doppler Effect can most commonly be heard by sirens as their sound pitches become higher as they approach an observer and drop as they pass.

5. “Doppler Radar” is used by meteorologists to study shifts in wind patterns detected by radar through the Doppler Effect to scan for wind shear or tornadoes.

6. “Redshift” is the tendency of sound and radio frequencies to decrease of have a lower pitch as they move away from an observer or to move toward the red end of the light spectrum.

7. “Blueshift” is the tendency of sound and radio frequencies to increase or have a higher pitch as they move toward an observer or move toward the blue end of the light spectrum.

8. Astronomers used the Doppler Effect to determine that the universe is expanding.

9. Since the universe is expanding, astronomers can use redshift to measure the distance from Earth to faraway galaxies.

— Dr. Bridges is a professor of history and geography living in Arkansas. He can be contacted at