Doppler

Definition

The Doppler Effect is the change in frequency or wavelength of a wave in relation to an observer moving relative to the source of the wave. In astronomy, it is used to determine the motion of stars and galaxies toward or away from us.

5 Must Know Facts For Your Next Test

1. Redshift occurs when a light source moves away from an observer, causing wavelengths to lengthen.
2. Blueshift occurs when a light source moves towards an observer, causing wavelengths to shorten.
3. The Doppler Effect can provide information on the radial velocity of celestial objects.
4. Spectral lines shift depending on whether a star or galaxy is moving towards or away from Earth.
5. The amount of shift in spectral lines can be used to calculate the speed at which an object is moving.

Review Questions

• What does redshift indicate about the motion of a celestial object?
• How does blueshift affect the wavelength of light observed?
• What kind of information can astronomers obtain using the Doppler Effect?

Related terms

Redshift: An increase in wavelength due to an object moving away from the observer.

Blueshift: A decrease in wavelength due to an object moving towards the observer.

Radial Velocity: The speed at which an object moves toward or away from an observer along their line of sight.