Doppler Effect
Image courtesy of NASA
By studying the motion of objects in the universe, astronomers have found that the motion
of most objects in space is redshifting, which supports the theory that the universe is expanding.
Light from a star can reveal its chemical make-up and its temperature. It can also show if it is moving toward Earth or away from Earth and how fast it is moving.
In order to better understand how astronomers can tell so much about a star just from the light it emits, you must first understand the phenomenon called the Doppler effect. This requires that astronomers also utilize the spectrum emitted from a star's elements and determine shifts in it. These shifts can tell a lot about the movement of a star.
View this presentation on the Doppler effect to see just how the wave phenomenon is an important tool of study of the stars and other celestial objects. Take notes on what the Doppler effect is, and what shifts in spectrum can reveal.
Download a printable version of the interactivity.
To learn more about the basics of the Doppler Effect, as well as the history of its discovery, view the video, 1842 - Doppler Effect from eMediaVA℠. As you view the video, consider how sound waves and light waves are related.
Calculating the Speed of Stars
Learn the formula that astronomers use to determine how fast an object in space, such as a star, is moving either toward or away from Earth. In this interactivity, click on each folder tab for information. Make sure to view the formula first, and then click on each example to see the equation in action. Click on the magnifying glass below each image to enlarge the information.
Download a printable version of the interactivity.
Doppler Effect Review
Review your knowledge of the Doppler effect and its use in astronomy by answering the questions in this non-graded activity. Once you have selected or entered each answer, click SUBMIT. Click the interactivity thumbnail, and then click NEXT to begin.