CLASS 9 · LEARNING KNOWLEDGE
Doppler effect and radial velocity – basic principles
How it works
The Doppler effect describes the change in frequency or wavelength of waves when the source and the observer move relative to each other. In astronomy, the effect is used with light waves to determine the radial velocity of celestial bodies. If an object moves toward the observer, the waves are compressed (blueshift), and if it moves away, they are stretched (redshift). The measured shift makes it possible to draw conclusions about the velocity along the line of sight.
Note
The direction and magnitude of the shift of spectral lines caused by the Doppler effect make it possible to determine the radial velocity of a celestial body relative to the observer.
The direction and magnitude of the shift of spectral lines caused by the Doppler effect make it possible to determine the radial velocity of a celestial body relative to the observer.
An example
What does a redshift in the spectrum of a star mean?
A redshift means that the star is moving away from the observer. The light is shifted to longer wavelengths because the source is moving away.
Try it yourself now
50 Exercises
To the learning unit →Own explanation and own practice exercises by AmyMath. Subject reference framework: Astronomy. The topic assignment may vary by federal state.