Don Backer, an astrophysicist at the University of California, Berkeley who discovered the first millisecond pulsar, died on 25 July. He was director of Berkeley’s Radio Astronomy Laboratory and the Allen Telescope Array (ATA) in Hat Creek, California – a collection of 42 dishes that recently began scanning the sky and searching for extraterrestrial intelligence.

“Don was a terrific scientist, innovative, clear in his thinking, and renowned as a mentor by many around the world,” says Berkeley radio astronomer Geoff Bower, who will take over as interim director of the ATA. “His death leaves a huge hole personally and professionally in the department.”

Backer was born in Plainfield, New Jersey in 1943 and received his astronomy Ph.D. from Cornell University in Ithaca, New York in 1971. He was a post-doctoral researcher at the National Radio Astronomy Observatory in Charlottesville, Virginia and then a researcher at NASA’s Goddard Space Flight Center in Greenbelt, Maryland.

He came to Berkeley in 1975 and, while there, studied black holes, pulsars, and, most recently, the emission spectrum of hydrogen from the early universe. In 1982, Backer and his colleagues discovered PSR B1937+21, the first known millisecond pulsar, an Earth city-sized star that rotates in a mere thousandth of a second. [corrected 7/28] The discovery astounded astronomers, who did not expect pulsars to rotate so fast.

Image Credit: Bob Rood