An increase in wavelength of radiation from an object moving away from the observer. The redshift of distant galaxies provides evidence for cosmic expansion. Greater redshift indicates faster recession and greater distance.
A decrease in wavelength and increase in frequency of electromagnetic radiation from an object moving toward the observe...
The change in frequency or wavelength of a wave relative to an observer moving relative to the source. In astronomy, it ...
A value describing the rate of the universe's expansion, named after Edwin Hubble. Its precise value remains debated, wi...
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