Edwin Hubble.

Edwin 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 generally mistakenly known for "Lemaître's law", discovered by Georges Lemaître, which is known more extensively as "Hubble's law".

Edwin's discoveries.

The universe goes beyond the milky way.

Edwin Hubble's arrival at Mount Wilson, California, in 1919 coincided roughly with the completion of the 100-inch (2.5 m) Hooker Telescope, then the world's largest telescope. At that time, the prevailing view of the cosmos was that the universe consisted entirely of the Milky Way Galaxy. Using the Hooker Telescope at Mt. Wilson, Hubble identified Cepheid variables (a kind of star) in several spiral nebulae, including the Andromeda Nebula and Triangulum. His observations, made in 1922–1923, proved conclusively that these nebulae were much too distant to be part of the Milky Way and were, in fact, entire galaxies outside our own.

Red shift increases with distance.

Combining his own measurements of galaxy distances based on Henrietta Swan Leavitt's period-luminosity relationship for Cepheids with Vesto Slipher and Milton L. Humason's measurements of the redshifts associated with the galaxies, he discovered a rough proportionality of the objects' distances with their red shifts. Though there was considerable scatter (now known to be due to peculiar velocities), he was able to plot a trend line from the 46 galaxies and obtained a value for the Hubble Constant of 500 km/s/Mpc, which is much higher than the currently accepted value due to errors in their distance calibrations.

Instruments.

Mt. Wilson Observatory: The hooker telescope.

The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a 5,715-foot (1,742 m) peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observatory contains two historically important telescopes: the 60 inches (1.5 m) Hale telescope built in 1908, and the 100 inches (2.5 m) Hooker telescope, which was the largest telescope in the world from its completion in 1917 until 1948.