1-152-404 - Ann Ronan Picture Library/Heritage-Images

Edwin Powell Hubble (1899-1953), American astronomer, in the obsevatory. Using the powerful hooker 100 inch reflector at Mount Wilson Observatory, Powell was the first to establish that there were other galaxies beyond our own. He also discovered the 'red shift' of the light from these distant galaxies, proving that the Universe is expanding, which he expressed mathematically as the Hubble Constant. Courtesy Astronomical Society of the Pacific