Professor Albert Whitford

Astronomer whose reddening law caused a revision of the size of the Milky Way
Click to follow
The Independent Online

Albert Edward Whitford, astronomer: born Milton, Wisconsin 22 October 1905; Director, Washburn Observatory, University of Wisconsin 1948-58; Director, Lick Observatory, University of California 1958-68, Professor of Astronomy and Astrophysics, University of California at Santa Cruz 1966-73 (Emeritus); President, American Astronomical Society 1967-70; married 1937 Eleanor Bell Whitelaw (died 1986; one son, two daughters); died Madison, Wisconsin 28 March 2002.

Albert Whitford was a pioneer of both the experimental science of astronomy and of the development of astronomy as a national research enterprise in America. He was the Director of the Washburn Observatory in Wisconsin from 1948 to 1958 and then for 10 years of Lick Observatory in California.

He came to astronomy through experimental physics, working to make quantitative measurements of starlight in the 1930s – an era when only photographic plates and the eye were used to estimate the brightnesses of stars. Joel Stebbins, his mentor and, later, long-time collaborator, had developed a photo-sensitive fibre galvanometer capable of measuring only the brightest stars in the sky. Whitford applied emerging vacuum-tube technology to the problem, and eliminated noise caused by cosmic ray showers in the air. This breakthrough enabled precise measurement of very faint stars.

Interest in their techniques was great, and Stebbins and Whitford observed extensively at the Mount Wilson Observatory, in California, then the greatest telescope of the time. The two of them knew personally the most significant astronomers of the 20th century, including Edwin Hubble.

When the brightnesses of stars could be accurately measured, the reddening and fading of starlight by interstellar dust in the Galaxy could be quantified and measured. This work resulted in the widely utilised Whitford reddening law, which remains largely correct to the present day. The discovery of the reddening law in the 1950s required a revision of the size of the Milky Way.

In fact, the development of a quantitative means to measure the brightnesses of stars, and the discovery of interstellar reddening, were essential to the measurement of the entire distance scale in the cosmos. Stebbins and Whitford discovered further that the dust toward the centre of the galaxy was much greater than in the direction opposite the centre, a finding that has become part of textbooks but was not at all obvious in the era before radio astronomy and digital surveys of the sky.

Albert Whitford was born in 1905 in Milton, Wisconsin, and graduated from Milton College in 1926. He earned his PhD in physics at the University of Wisconsin in 1928 and joined the faculty there in 1936, directing its Washburn Observatory from 1948. In 1940 Ernest Lawrence recruited him to work on radar at the MIT Radiation Laboratory. His work on short-wavelength radar permitted finer details to be discerned, and the periscopes of U-boats surfacing at night could be discovered by aeroplanes. This work contributed to the Allied victory in the Battle of the Atlantic.

Following the Second World War, Whitford applied the photoelectric photometer to the most ambitious problems of the day, including the study of the most distant galaxies known, and in the search for the obscured nucleus of the Milky Way.

In 1958 he left the directorship of Washburn Observatory to become Director of Lick Observatory at the University of California. He took charge of turning the new three-metre telescope, then the second largest in the world, into a powerful research instrument. Nationally, he managed the first decadal survey of astronomy, the Whitford report, in 1962, which recommended the founding of a national observatory in the United States. The model of 10-year surveys of the needs of astronomy has been maintained since, and has been held up as an example to scientists in other fields. The most recent survey in the US recommended construction of a next-generation space telescope, to be operational by 2010.

As Director of Lick Observatory, Whitford oversaw the very difficult transition of the observatory from the last mountain-top enclave of astronomers to a modern university-based astronomy department at the University of California at Santa Cruz. The course he helped found has become one of the premier courses in the world, and it was within the UC that the idea of building the Keck 10m telescopes in Hawaii (currently the world's largest) was developed.

In 1968 Whitford retired as Director and resumed an active research career, including rigorous trips to Chile to observe at the newly commissioned telescopes there. He was the first to quantify the metal abundances and properties of stars in the central bulge of the Milky Way and to relate these stars to the properties of external galaxies.

He continued to work at Santa Cruz for many years after official retirement in 1973.

R. Michael Rich

Comments