Jesse Greenstein, 93; Astronomer Gave Insight on Quasars
Jesse L. Greenstein, a Caltech astronomer and authority on the evolution and composition of stars, has died. He was 93.
Greenstein died Monday in Arcadia from complications of surgery to repair a hip he broke in an fall on Oct. 18.
During a 72-year career, Greenstein helped discover some of the strangest denizens of our universe, from extremely bright quasars to faint, burned-out stars called white dwarfs. His research helped shift a long-held view of the night sky as a serene, twinkling tableau of stars to one of a violent, swirling space filled with black holes, exploding stars and jets of scalding gas.
“These were explosive, wild phenomena that had never been dreamed of,” said Marshall Cohen, an emeritus professor of astronomy at Caltech who worked closely with Greenstein.
Greenstein earned a doctorate from Harvard in 1937, when astronomers were limited by what they could see through relatively small optical telescopes. In 1955, he took up the emerging field of radio astronomy, which offered astronomers some of the first views of a hot and violent universe.
Greenstein helped start the Owens Valley Radio Observatory and the National Radio Astronomy Observatory; the latter operates major radio telescope facilities around the country.
“A lot of the things he leaves in his legacy are the bread and butter of today’s astronomy,” said a Caltech astronomer, Anneila I. Sargent. “They are part of the fabric of our lives.”
Truly captivated by star-gazing, Greenstein spent more than 1,000 nights -- not a world record but close -- sitting at telescopes and developing photographic plates to unlock the secrets of the stars he called “inaccessible but convenient experimental laboratories.”
At age 85, Greenstein returned to Caltech’s Palomar Observatory north of San Diego for one last night of observing. He gamely climbed into the small observing cage suspended above the Hale telescope’s 200-inch primary mirror.
“You also had to have a tough bladder,” he recalled of his past observing exploits. “If it was a good night, you stayed up [in the cage] from 7 o’clock to 5. That’s 10 hours!”
Greenstein, who had broad interests, is credited with piecing together the physics of many astronomical objects. He measured the most basic makeup of stars, helped determine that nuclear reactions within stars could produce all naturally occurring chemical elements and probed magnetic fields strung out across interstellar space.
He is credited, along with Caltech astronomer Maarten Schmidt, with helping to decipher the nature of quasars, one of the biggest astronomical mysteries of the last half-century.
Scientists, who once thought quasars were strange, bright stars within our own galaxy, realized by 1963 that they were the most distant objects in the universe. The scientists surmised that quasars therefore had to be much brighter than stars and were perhaps galaxy-sized objects.
Greenstein and Schmidt concluded that the objects were far more compact and energetic. This key insight is considered one of the 53 most important astronomical findings of the 20th century by two leading journals. It helped lead to current thinking that quasars are powered by super-massive black holes that emit light as they gobble vast amounts of matter.
Greenstein came to Caltech in 1948, just as the university was finishing construction of the Hale telescope, the largest of its kind for more than 40 years. As the founding member of the Caltech astronomy department, he taught all of its courses during his first year and oversaw the growth of the department into one of the most prestigious in the world.
He was a father figure to several generations of astronomers who still recall his presiding over the intense lunch gatherings at the Caltech Athenaeum.
“He was mentally very quick and could do back-of-the-envelope calculations right in front of you. It was very entertaining,” Cohen said.
Added Sargent, president of the American Astronomical Society: “I wouldn’t be the astronomer I am today without him.”
A native of New York City, Greenstein began his lifelong interest in astronomy when he was 8 years old and received a brass telescope from his grandfather. He went on to build his own prism spectroscope in his family’s basement.
He attended Harvard University as an undergraduate, but gave up his studies to help run his family’s real estate business during the Great Depression. He returned to Harvard in 1934 and completed his doctorate three years later.
Greenstein worked for the University of Chicago for 11 years before joining Caltech, where he remained until his retirement in 1979. He published an average of 8 1/2 papers per year, a phenomenal rate that continued long after his formal retirement.
He was elected to the National Academy of Sciences in 1957, was named California scientist of the year in 1964, was awarded the NASA Distinguished Public Service Medal in 1974 and won the Gold Medal of the Royal Astronomical Society in 1975.
Greenstein’s wife of 68 years, Naomi Kitay Greenstein, died earlier this year. They met when Greenstein was a 16-year-old undergraduate at Harvard. Her renowned hospitality and party-giving were long considered a major part of the Caltech astronomy department’s appeal.
Greenstein is survived by two sons, Peter of Oakland and George of Amherst, Mass.
