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Do orbital motions between galaxies affect calculations of the cosmological redshift?

Steve Davis, Greenacres, Washington
RELATED TOPICS: COSMOLOGICAL REDSHIFT
Markarians Chain

Yes, they do. The observed redshift, or wavelength shift due to motion, of a galaxy’s characteristic light spectrum is a combination of the galaxy’s motion with respect to its neighbors (“peculiar velocity”) and the expansion of the universe (“cosmological redshift”). The latter only corresponds to objects moving away from us — their light shifts to the red end of the electromagnetic spectrum.

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