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
Extragalactic background light near-infrared. However, it has been proposed that these analyses have been contaminated by zodiacal light. Recently, two independent groups using different technique have claimed the detection of the EBL in the optical with no contamination from zodiacal light. There are also other techniques that set limits to the background. It is possible to set lower limits from deep galaxy surveys. On the other hand, VHE observations of extragalactic sources set upper limits to the EBL. In November 2018, astronomers reported that the EBL amounted to photons. There are empirical approaches that predict the overall SED of the EBL in the