Prominent British-born astronomer and comet-chaser Brian Marsden has died at the age of 73 after a long illness, the Harvard-Smithsonian Center for Astrophysics said.

Marsden was best known for predicting the return of Comet Swift-Tuttle in 1992, and played a key role in the "demotion" of Pluto to dwarf planet status, the Center said in a statement.

"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, who was a senior astronomer at the Smithsonian Astrophysical Observatory and director emeritus of the Minor Planet Center, died on November 18.

He specialized in celestial mechanics and astrometry, tracking data on the positions of asteroids and comets and computing their orbits.

Marsden was born in Cambridge in 1937, and earned degrees from Oxford and Yale. He leaves behind two children, three grandchildren and a sister.