The astronomical community lost two longtime, eminent members in November with the deaths of asteroid-tracker Brian Marsden and cosmologist Allan Sandage.
Marsden, who died Nov. 18 at age 73 after a long illness, served as an astronomer at the Smithsonian Astrophysical Observatory in Cambridge, Mass.
He specialized in tracking asteroids and comets and served as director of the Minor Planet Center, the official clearinghouse of data for these objects, from 1978 to 2006.
Marsden’s work was crucial in helping to track potentially Earth-threatening objects, scientists said. The New York Times, in fact, once described him as a “Cheery Herald of Fear.”
Among his many accomplishments, Marsden accurately predicted that Comet Swift-Tuttle — which had last been seen in 1862 — would return to the inner solar system in 1992 rather than 1981, as conventional wisdom had held.
“Brian was one of the most influential comet investigators of the 20th century,” said Charles Alcock, director of the Harvard-Smithsonian Center for Astrophysics, “and definitely one of the most colorful!” Marsden also played a key role in the demotion of Pluto from full planet to dwarf planet. He once proposed that Pluto should be cross-listed as both a planet and a “minor planet,” and assigned it the asteroid number 10,000.
That proposal was not accepted. However, in 2006, a vote by members of the International Astronomical Union created a new category of “dwarf planets,” which includes Pluto, Eris and several other objects. Pluto was designated minor planet 134340. This decision remains controversial.
Marsden was born in 1937 in Cambridge, England. He received an undergraduate degree in mathematics from Oxford and a doctorate from Yale.
Sandage, a well-known cosmologist, died Nov. 13 of pancreatic cancer at age 84. He was a longtime astronomer for the Carnegie Observatories, working for years with the telescopes at Mount Wilson and Palomar in California.
During the early 1950s, Sandage served as observing assistant to the famous astronomer Edwin Hubble — who discovered that the universe is expanding — at Mount Wilson and Palomar.
When Hubble died in 1953, Sandage focused on carrying on Hubble’s research, working to determine the rate at which the universe is expanding. Sandage continued this research for nearly 60 years.
Even though Sandage officially retired Sept. 1, 1997, he was still actively working until August of this year.
Sandage made seminal contributions in several areas of astronomy, scientists said. He helped date the ages of stars and the expansion age of the universe more accurately, for example. Sandage also helped advance scientists’ understanding of galaxy formation and evolution.
Sandage led the first major distance — or redshift — surveys of galaxies, from which he created a 3-D map to explore galaxy distribution and the dynamics of the nearby universe. He was the first to recognize the existence of quasars — the brightest objects in the universe — that did not emit strong radio waves.
Sandage was born in Iowa City, Iowa, in 1926. He received a bachelor’s degree from the University of Illinois and a doctorate from Caltech.