An Etymological Dictionary of Astronomy and Astrophysics

The deduction based on the observational fact that the greater the → distance to a → galaxy, the greater the → redshift in its → spectral lines (→ Doppler effect). The observations strongly indicate that galaxies appear to be moving away from us with speeds proportional to their distance. This is in agreement with the overall → expansion of the → Universe.

See also: → expand; → -ing; → Universe.