In 1919, Edwin Hubble was hired to work at the Mount Wilson Observatory as a junior astronomer. He would help complete the construction of the Hooker telescope. In 1929 Hubble made an interesting discovery. He discovered that the farther away a galaxy is from Earth, the faster it seems to move away. This "expanding universe" principle would eventually develop into the 'Big Bang Theory;. He would leave the observatory in 1942 to serve in World War II. For his service he would be awarded the Medal of Merit.
During his time at the Observatory, he married Grace Burke in 1924. This couple would never have children. He lived the rest of his life with his wife Grace until his death on September 28, 1953. He had died of a stroke due to Cerebral Thrombosis which causes blood to be drained from the brain.