Edwin Powell Hubble

Edwin Powell Hubble was born on November 20, 1889 in Marshfield, Missouri in the home of his maternal grandparents.  A year later his parents John Powell and Virginia Lee Hubble moved to Marshfield.  His father worked in insurance and often moved with his wife and children and rented out the family's house in Marshfield.  In 1895 Hubble moved back into the family home in Marshfield with his mother and siblings, where he started school.  In 1901 the family moved to Wheaton, Illinois, where Hubble went to middle and high school.  In school Hubble was a good athlete and did well in all his subjects, excepting spelling.  Young Hubble was an avid reader and enjoyed the novels of Jules Verne.  In 1906 Hubble began at the University of Chicago, where he earned his bachelors in mathematics and astronomy in 1910.

After finishing his bachelors Hubble went to England, where he studied law, at the insistence of his dying father, at Queens College, Oxford on a Rhodes Scholarship.  He remained in England for three years.  Upon returning to the United States Hubble taught high school mathematics, physics and Spanish, also coaching basketball, for a year.  After a year teaching he returned to his passion, astronomy, and began studying at the Yerkes Observatory at the University of Chicago, finishing his Ph.D. in 1917.  His dissertation was titled "Photographic Investigations of Faint Nebulae"  Hubble served in the United States Army during World War I, rising to the rank of major.  In 1919 Hubble accepted a position at the Mt. Wilson Observatory, in Pasadena, California, where he remained on staff until his death.  During World War II Hubble  worked for the Army at the Aberdeen Proving Ground, in Aberdeen, Maryland, where he worked on ballistics and for which he was awarded the Legion of Merit.

Hubble's arrival at the Mt. Wilson Observatory coincided with the instillation of the Hooker Telescope, a 2.5 meter telescope, which at the time was the largest in the world.  At the time most astronomers believed that the Milky Way Galaxy was the extent of the universe and that the fuzzy objects called nebulae were contained within it.  Using the Hooker Telescope, Hubble was able to show that some of these fuzzy objects contained stars and were much too distant to be inside of the Milky Way.  Hubble showed that some of these objects were in fact galaxies and he devised a method of categorizing them based on their shape, called the Hubble Sequence, which is still used today classify galaxies.  Hubble's most astonishing discovery came from studying the spectra of 46 galaxies in which he showed that the further galaxies were from each other the faster that they were moving away from each other.  Based on this observation Hubble concluded that the universe was expanding at a constant rate (it later was determined that the rate of expansion is actually increasing).  With his colleague Milton Humason, he estimated that the rate of expansion is 500 Km per second per megaparsec.  So a galaxy one megaparsec away is receding from the Milky Way at a rate of 500Km/second (a mega parsec is one million parsecs, each 3.3 light years or about 3.08x10²²meters).  This is called the Hubble Constant and astronomers have been refining the measurement ever since.

Honors won by Hubble include the Bruce Medal, awarded by the Astronomical Society of the Pacific, the Franklin Medal, awarded by the Franklin Institute, and Gold Medal, the highest honor of the Royal Astronomical Society of Great Britain.  He was never awarded the Nobel Prize because it was not till after his death that astronomy was considered a subject for which the Nobel Prize in physics could be awarded and the Nobel Prize is not awarded posthumously. In addition to the Hubble Space Telescope, a telescope orbiting the earth, an asteroid and a crater on the moon are also named after Hubble.  In 2008 the United States Postal Service issued a stamp honoring Hubble.

Hubble died on September 23, 1953.


References:

Christianson, Gale E.; Edwin Hubble: Mariner of the Nebulae; University of Chicago Press; 1996

Anonymous; Edwin Hubble Biography at edwinhubble.com

Anonymous: Edwin P. Hubble at Hubble Space Telescope Website (hubble.nasa.gov)

Edwin Hubble Wikipedia Entry

Gerard Henri de Vaucouleurs

Gerard de Vaucouleurs was born on April 25, 1918 in Paris, France. From an early age he was interested in astronomy, observing the moon from the balcony of his family's apartment using a marine telescope he had borrowed. A few years later his mother purchased a telescope for him and he used it to observe various stellar occulations, planetary conjunctions, an eclipse and with his small telescope he photographed close approaches by Mars to the Moon and the Pleiades star cluster.

De Vaucouleurs received a B.Sc. in 1936 from the Lycee Charlemagne in Paris and went to the Sorbonne from 1937-1939 for training in physics, astronomy and physics. Starting in 1939 de Vaucouleurs worked briefly at the private observatory of Julien Peridir, but after two months their association was interrupted by the outbreak of World War II. During the war De Vaucouleurs served as an artillery officer. In 1943 de Vaucouleurs re-enrolled at the Sorbonne to work on his doctoral degree, graduating 1949 after completing a dissertation on the molecular (Rayleigh) scattering of light in gases and liquids. In 1944 he married his first wife Antionette, who was also interested in astronomy.

De Vaucouleurs, interested in extragalactic astronomy did not see a future for himself in France, emigrated first to England where he ran a weekly science radio program for the BBC. The frequently cloudy skies of England led de Vaucouleurs to Australia, where he went to Australian National University in Canberra and in 1951 he got an appointment to the Mt. Stromlo observatory where he became the first research fellow at ANU to preform radial velocity studies of galaxies in the unexplored southern sky. He received a D.Sc. degree from ANU in 1957 for research in molecular physics, optics, photography, astronomy and astrophysics. In 1957 de Vaucouleurs emigrated to the United States where he took a position working at the Lowell Observatory, continuing his observations of galaxies and Mars. In 1958 he moved to Harvard where he planned a program of precise observations of Mars which were used for NASA's Mariner 9 program.

In 1960 de Vaucouleurs moved to the University of Texas at Austin, where he spent the next 35 years observing galaxies at the McDonald Observatory. It was after his move to Texas that de Vaucouleurs began producing his Reference Catalog of Bright Galaxies, the first in 1964, the second in 1976, and the third in 1991. These catalogs were a monumental effort to collect and homogenize all the basic data on 2599 bright galaxies. The observations used to produce these works led de Voucouleurs to believe that the value of the Hubble constant was about 100 km/s/mpc.

The Hubble constant (Ho) is a constant that relates the velocity (v) of a receding galaxy to the distance (d) from an observer. The Hubble law equation is: v=Hod. The law was first published in 1929 by Edwin Hubble who had noticed a relationship between the doppler redshift of spectrum lines and estimated distances from the Milky Way of receding galaxies. This law is an expression of the expansion of the universe. At the time of de Voucouleurs pronouncement, Allan Sandage and Gustav Tammann had presented a value for Ho of about 50. This dispute was unresolved for years and remained at the time of de Vaucouleurs death. Various methods have been used to estimate Ho and it is currently believed to be about 70.

De Vaucouleurs received many awards for his work, including the Herschel Medal from the Royal Astronomical Society in 1980 and the Henry Norris Russel Prize from the American Astronomical Society in 1988. He was became a member of the U. S. National Academy of Sciences in 1986.

De Vaucouleurs died on October 7, 1995.

References:

Burbidge, Margaret; "Gerard de Vaucouleurs"; in Biographical Memoirs, Vol. 82, National Academy Press; 2003

Buta, Ronald; "Gerard Henri de Vaucouleurs, 1918-1995"; Bulletin of the American Astronomical Society(1996)28:1449-1450

"In Memoriam Gerard de Vaoucouleurs" at www.utexas.edu

Hubble's Law Wikipedia Entry