About Edwin Arthur Hubble
Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer who profoundly changed our understanding of the universe by demonstrating the existence of galaxies other than our own, the Milky Way.
He also discovered that the degree of "Doppler shift" (specifically "redshift") observed in the light spectra from other galaxies increased in proportion to a particular galaxy's distance from Earth.
This relationship became known as Hubble's law, and helped establish that the universe is expanding. Hubble has sometimes been incorrectly credited with discovering the Doppler shift in the spectra of galaxies, but this had already been observed earlier by Vesto Slipher, whose data Hubble used.