One of the wavelengths of light emitted by hydrogen atoms

Last updated: 7/10/2022

One of the wavelengths of light emitted by hydrogen atoms under normal laboratory conditions is at λ = 656.3 nm in the red portion of the electromagnetic spectrum. In the light emitted from a distant galaxy this same spectral line is observed to be Doppler-shifted to λ = 954.7 nm, in the infrared portion of the spectrum. Part A How fast are the emitting atoms moving relative to the earth? Express your answer in meters per second to three significant figures.