Edwin Powell Hubble was born in 1889 in Missouri, excelled as a student athlete at the University of Chicago, and studied law at Oxford on a Rhodes Scholarship before returning to astronomy—a field he pursued after a brief legal career dissatisfied him. At Mount Wilson Observatory in California he gained access to the 100-inch Hooker telescope, then the largest in the world, and used it to settle questions that had divided astronomers for decades.

In 1924 Hubble identified Cepheid variable stars in the Andromeda Nebula, calculating distances that proved it was a separate galaxy millions of light-years away, not a nearby gas cloud within our own Milky Way. The discovery enlarged the universe overnight. Working with Milton Humason, he then analyzed galactic redshifts and found a linear relationship between distance and recessional velocity—the observation later enshrined as Hubble's Law and foundational evidence for an expanding universe.

Hubble's meticulous plates and classifications also produced the tuning-fork diagram of galaxy shapes still used in astrophysics courses. Though he never received the Nobel Prize— astronomy was not yet eligible— his name was attached to the Hubble Space Telescope launched in 1990. He died in San Marino, California, in 1953, having turned cosmology from a speculative branch of philosophy into an observational science.

1. 1919

   Mount Wilson Appointment

   Joined the observatory where he would conduct his landmark extragalactic research.

2. 1924

   Andromeda Cepheids

   Resolved Cepheid variables in Andromeda, proving it lies outside the Milky Way.

3. 1929

   Redshift Paper Published

   Reported the linear relation between galaxy distance and recessional velocity.

4. 1948

   Palomar Work Begins

   Contributed to commissioning the 200-inch Hale telescope at Palomar Observatory.

5. 1953

   Death in California

   Died of a cerebral thrombosis; asteroid and space telescope later bore his name.