Edwin Hubble Edwin Hubble Edwin Powell Hubble (November 20, 1889 – September 28, 1953) was an American astronomer. He played a crucial role in establishing the fields of extragalactic astronomy and observational cosmology and is regarded as one of the most important astronomers of all time. Hubble discovered that many objects previously thought to be clouds of dust and gas and classified as "nebulae" were actually galaxies beyond the Milky Way. He used the strong direct relationship between a classical Cepheid variable's luminosity and pulsation period (discovered in 1908 by Henrietta Swan Leavitt) for scaling galactic and extragalactic distances. Hubble provided evidence
First Cambridge Catalogue of Radio Sources axis is not exactly East-West. The survey found radio sources in close proximity to four of the five major extragalactic nebulae, namely M31, M33, M101 and M51, corresponding to sources 00.01, 01.01, 14.01 and 13.01 respectively. Only M81 had no observed radio source. The isotropy of the sources lead the team to conclude that radio stars were either local phenomena, or extragalactic. First Cambridge Catalogue of Radio Sources The First Cambridge Catalogue of Radio Sources (1C) refers to the catalogue listed in the article "Ryle M, Smith F G & Elsmore B (1950) MNRAS vol 110 pp508-523 "A Preliminary Survey