Eminent Astronomers Brian Marsden, 73, and Allan Sandage, 84, Die From Illnesses
Astronomer Brian Marsden died Nov. 18, 2010, at the age of 73. He was the longtime director of the Minor Planet Center, a clearinghouse of information about comets and asteroids.
Credit: Harvard-Smithsonian Center for Astrophysics
This story was updated at 4:13 p.m. EST.

The astronomical community lost two longtime, eminent members in the last week with the deaths of Brian Marsden and Allan Sandage.

Brian Marsden

Marsden, who died yesterday (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."

"Brian was a tireless asteroid hunter who, with limited funding and an incredibly small staff, seemed to be at the helm whenever a new space-rock report came in, and always willing to explain things to the media to help quell public fear and, in general, spread good science," said veteran space reporter Robert Roy Britt, editor-in-chief of TechMediaNetwork, which includes SPACE.com. "He was among a handful of pioneers who helped elevate asteroid hunting and the reporting of incoming space rocks to a fine and useful science. And he was a heckuva nice guy who sought not fame but simply wanted to serve the public day after day, night after night."

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 twentieth 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 10000.

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 Ph.D. from Yale.

Allan Sandage

Cosmologist Allan Sandage 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 three-dimensional 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 didn't emit strong radio waves.

Sandage was born in Iowa City, Ia., in 1926. He received a bachelor's degree from the University of Illinois and a Ph.D from Caltech.