Astronomy & Space Science · AST-100
Doppler Shift, Redshift & Blueshift: Advanced Connections
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Overview
The larger system around Doppler Shift, Redshift & Blueshift
The Doppler effect changes the observed wavelength of radiation when a source and observer have relative motion along the line of sight. Receding sources shift spectral features toward longer wavelengths, while approaching sources shift them toward shorter wavelengths.
Doppler measurements reveal radial velocity but not the full three-dimensional velocity by themselves. Combining them with proper motion and distance can recover space motion for nearby objects.
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References & evidence
Source library for this chapter
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- 01The Doppler EffectOpen source ↗
OpenStax Astronomy 2e
View claim-by-claim traceability3 verified claims
For ordinary Doppler motion, successive wavefronts arrive more widely spaced when the source recedes and more closely spaced when it approaches.
supported · checked Sep 22, 2026The Doppler effect changes the observed wavelength of radiation when a source and observer have relative motion along the line of sight.
supported · checked Sep 22, 2026Spectrographs measure line positions with high precision.
supported · checked Sep 22, 2026