Astronomer; b. 20 November 1889 (Marshfield, Mo, USA), d. 28 September 1953 (San Marino, Ca.).
Edwin Hubble's family moved from Missouri, where Edwin was born, to Chicago when Edwin was nine years old. The young Hubble excelled in athletics, boxing and basketball but was academically good enough to receive a Rhodes scholarship for Oxford University, where he studied law. He received his B.A. in 1912 and returned to the USA to establish a legal practice in Kentucky.
Finding himself bored with law, Hubble returned to university to study astronomy at the University of Chicago. He received his PhD in 1917. After return from duty during World War I he worked at the Mount Wilson Observatory near Pasadena in California, studying the properties of galaxies. He discovered that some nebulae contained pulsating stars called Cepheid variables, for which the correlation between the period of pulsation and absolute magnitude of luminosity was already established. This allowed him to show that these galaxies were not part of the Milky Way, as was believed at the time, but several hundred thousand light-years away. The announcement of this finding in 1924 led to a revision of astronomical theory.
Hubble then concentrating on the determination of distances of galaxies and observed in 1927 that all galaxies were receding from the Milky Way. In 1929 he refined this finding by showing that the universe was expanding in such a way that the ratio of the speed of the galaxies to their distance is a constant, now called Hubble's constant. His initial calculation of the constant was in error and made the Milky Way appear larger than all other galaxies. Modern astronomy has rectified this, and Hubble's discoveries form the basis of modern cosmology.
Hubble's observations caused Einstein to retract his invention of a "cosmological constant" he had introduced to make the universe static and immobile. Einstein visited Hubble in 1931 to acknowledge that Hubble's work had helped him to rectify his error.
In 1942 Hubble left the Mount Wilson Observatory to offer his services as a scientist in the war against Nazi Germany. He returned to Mount Wilson after the war and was instrumental in establishing the bigger telescope at the Mount Palomar Observatory.
Edwin Powel Hubble. Encyclopaedia Britannica 15th ed. (1995).
edwinhubble.com (2002) Edwin Powell Hubble. http://www.edwinhubble.com/hubble_bio_001.htm (accessed 25 September 2004).
Wands, D., Edwin Hubble. http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Hubble.html (accessed 25 September 2004).