John Norris Bahcall, 70, an astrophysicist who found a new way to study the sun and was a major force behind the Hubble Space Telescope, died Wednesday at New York-Presbyterian Hospital of a rare blood disorder, according to the Institute for Advanced Study in Princeton, N.J., where Bahcall was a faculty member for 35 years.
Dr. Bahcall was born in Shreveport, La., in 1934. He was educated at Louisiana State University and the University of California, Berkeley, and earned a doctorate at Harvard in 1961.
In 1964, he was working at the California Institute of Technology when he proposed that scientists could figure out why the sun shines by measuring the number of solar neutrinos - ghostly particles that arrive on Earth.
At the time, collaborator Raymond Davis was trying to catch neutrinos in a chemical tank in a South Dakota gold mine. When too few were found, many thought the experiment was flawed. Dr. Bahcall said calculations by physicists - including himself - were flawed and that the tiny particles changed their shape. Experiments in the 1990s finally proved him right.
In 1996, Dr. Bahcall wrote about what was learned: "The nuclear reactions that produce the neutrinos also cause the sun to shine."
In the 1970s, he was a leader of the effort to create the Hubble, which was launched in 1990. He pushed for the instrument's survival until the end of his life.
He joined the Institute for Advanced Study, which had been Albert Einstein's academic home, in 1968.
Mo Mowlam, 55, a British politician whose no-nonsense style helped forge Northern Ireland's landmark peace accord, died in London yesterday after hitting her head in a fall.
Gideon Nieuwoudt, a former South African police colonel who confessed to a role in the death of anti-apartheid activist Steve Biko and was convicted of killing several other opponents of white rule, died in prison this week in Johannesburg. He was in his mid-50s.