Edwin Powell Hubble was an American astronomer who played a crucial role in establishing the field of extragalactic astronomy and is generally regarded as one of the most important observational cosmologists of the 20th century. Hubble is known for showing that the recessional velocity of a galaxy increases with its distance from the earth, implying the universe is expanding.
Edwin Hubble is also known for providing substantial evidence that many objects then classified as “nebulae” were actually galaxies beyond the Milky Way (this day in 1924). Hubble’s name is most widely recognized for the Hubble Space Telescope which was named in his honor.
Hubble’s findings fundamentally changed the scientific view of the universe. Supporters of Hubble’s expanding universe theory state that Hubble’s discovery of nebulae outside of our galaxy helped pave the way for future astronomers. Hubble also devised the most commonly used system for classifying galaxies, grouping them according to their appearance in photographic images. (below: “Pillars of Creation” in the Eagle nebula taken from Hubble telescope)
At the time, the Nobel Prize in Physics did not recognize work done in astronomy. Hubble spent much of the later part of his career attempting to have astronomy considered an area of physics, instead of being its own science. He did this largely so that astronomers—including himself—could be recognized by the Nobel Prize Committee for their valuable contributions to astrophysics. This campaign was unsuccessful in Hubble’s lifetime, but shortly after his death, the Nobel Prize Committee decided that astronomical work would be eligible for the physics prize. However, the prize is not one that can be awarded posthumously. (from Wikipedia and cute-calendar.com)