redshift
Sign in to savethumb|upright|Spectral line|Absorption lines in the [[visible spectrum of a supercluster of distant galaxies (right), as compared to absorption lines in the visible spectrum of the Sun (left). Arrows indicate redshift. Wavelength increases up towards the red and beyond (frequency decreases).]]
AI overview
Redshift is the stretching of light waves from distant galaxies, causing their light to shift toward the red end of the spectrum—a shift that scientists can measure by comparing spectral lines to those of nearby objects like the Sun. This phenomenon matters because it helps astronomers determine how far away galaxies are and provides evidence about the expansion of the universe.
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Article
25 sectionsContents
- History
- Physical origins
- Doppler effect
- Cosmological <span class="anchor" id="Cosmological"></span>
- Distinguishing between cosmological and local effects
- Gravitational redshift
- Summary table
- Measurement
- Observations in astronomy
- Local observations
- Extragalactic observations
- Highest redshifts
- Redshift surveys
- Effects from physical optics or radiative transfer
- Blueshift
- Doppler blueshift
- Gravitational blueshift
- Blue outliers
- Cosmological blueshift
- See also
- References
- Sources
- Articles
- Books
- External links
thumb|upright|Spectral line|Absorption lines in the [[visible spectrum of a supercluster of distant galaxies (right), as compared to absorption lines in the visible spectrum of the Sun (left). Arrows indicate redshift. Wavelength increases up towards the red and beyond (frequency decreases).]]
In physics, a redshift is an increase in the wavelength, or equivalently, a decrease in the frequency, of electromagnetic radiation (such as light). The opposite change, a decrease in wavelength and increase in frequency and energy, is known as a blueshift.