CLASS 9 · LEARNING KNOWLEDGE
Redshift and the expansion of the universe – basics
How it works
Redshift is a phenomenon in which spectral lines of light appear shifted to longer wavelengths. For many distant galaxies, this is interpreted as a consequence of the expansion of the universe. In general, the following applies: the farther away a distant galaxy is, the greater its redshift. In nearby galaxies, however, proper motion can override this relationship. Redshift is denoted by the letter z. It provides clues about distance and about the expansion of the universe.
Note
Redshift describes the shift of spectral lines toward the long-wave, red part of the spectrum. It is calculated using z = (observed wavelength – rest wavelength) / rest wavelength. For z > 0 there is a redshift, for z < 0 a blueshift. For distant galaxies, redshift is usually an indication of the expansion of space; for nearby objects, the Doppler effect due to their proper motion can also be important.
Redshift describes the shift of spectral lines toward the long-wave, red part of the spectrum. It is calculated using z = (observed wavelength – rest wavelength) / rest wavelength. For z > 0 there is a redshift, for z < 0 a blueshift. For distant galaxies, redshift is usually an indication of the expansion of space; for nearby objects, the Doppler effect due to their proper motion can also be important.
An example
What does it mean if the light of a distant galaxy shows a high redshift?
A high redshift generally means that the distant galaxy is strongly receding from us in the course of the expansion of the universe and that its spectral lines have been shifted noticeably to longer wavelengths.
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.