Short answers, pulled from the story.
Edwin Hubble was an American astronomer who lived from 1889 to 1953 and helped establish extragalactic astronomy and observational cosmology. He proved that objects classified as nebulae were actually galaxies beyond the Milky Way, and in 1929 he found that a galaxy's recessional velocity increases with its distance, a relationship known as Hubble's law.
Using the 100-inch Hooker Telescope at Mount Wilson Observatory, Hubble identified Cepheid variable stars in nebulae including the Andromeda Nebula and the Triangulum Nebula. His 1924 observations showed these objects were far too distant to belong to the Milky Way, proving they were entire galaxies of their own.
Hubble's law states that the greater the distance between two galaxies, the greater their relative speed of separation, which implies the universe is expanding. Hubble established it in 1929 by combining his distance estimates with redshift measurements from Vesto Slipher and his assistant Milton L. Humason.
Hubble resisted that interpretation of his own data. He preferred the term "apparent" velocities, and according to Allan Sandage he favored a model with no true expansion, suggesting the redshift might represent a hitherto unrecognized principle of nature.
During Hubble's life the Nobel Prize in Physics did not cover astronomy, so his work was ineligible. He campaigned to have astronomy considered part of physics, but the change came only shortly after his death in 1953, when the Nobel Committee decided astronomical work would qualify.
Georges Lemaitre predicted the redshift-distance relation from Einstein's equations and published observational support in French two years before Hubble's law was established. In 2011, Mario Livio reported in Nature that Lemaitre himself made the redactions in the 1931 English translation of his 1927 paper, seeing no point in republishing content already reported by Hubble in 1929.