| Dawn
Levy, News Service Stanford University
Astronaut
and solar physicist Loren Acton will deliver the 21st annual
Bunyan Lecture at 7 p.m. Wednesday, May 2, in Terman Auditorium.
The talk, which is free and open to the public, is titled
"The Magnetic Personality of the Universe." Stanford's
Astronomy Program in the Physics Department sponsors the
Bunyan Lectures, which are intended to bring the latest
findings in cosmology research to the public and explore
their impact on society.
"The
study of magnetism has been a dominant factor in the destiny
of the human species," Acton said in a phone interview.
"Our lives have been changed by electronics. What happens
to us as people is often determined by our ability to control,
understand and use electronic forces."
Scientists
have made a number of discoveries recently about magnetic
fields in space, he said. Acton's own work revolves around
the largest magnetic laboratory in our collective backyard
-- the sun. A professor of physics at Montana State University
in Bozeman since 1993, Acton leads a research effort to
monitor changes in the sun's blistering-hot outer corona.
Temperatures in the corona can exceed 1 million degrees,
Acton said, and the heat induces atoms in the corona to
emit X-rays. Acton helped to design and build an X-ray telescope
that monitors these emissions. The telescope orbits the
Earth as part of a Japanese satellite mission called YOHKOH,
which means "sunbeam."
YOHKOH
has taken more than 4 million pictures of the sun since
its launch a decade ago. The YOHKOH team anticipates continuing
the observations until 2008, when the satellite is projected
to reenter the Earth's atmosphere. Acton said study of the
solar corona over a long period of time lets researchers
link coronal changes to the solar cycle, in which the sun's
magnetic field swaps north with south every 22 years. Acton
will present results from the project to the scientific
community at 4 p.m. Thursday, May 3, in a technical talk
titled "Solar Cycle Dependence of Coronal Activity
as Observed by Soft X-ray Telescope on YOHKOH." The
talk will be held in the second floor conference room of
the Varian Building.
The
allure of space had a lot of influence on Acton when he
was in school. Space science opened up a host of new ways
to explore the world. "The space program was just taking
off," he said. "It was like taking off your dark
glasses you could see the universe in a way that you'd
never been able to before."
His
doctoral dissertation at the University of Colorado in 1965
dealt with very early measurements of solar X-rays. "It
was so much fun, I've been doing it ever since," he
said.
Acton
worked in Palo Alto at Lockheed research labs from 1964
to 1993. He was working there in 1977 when NASA accepted
Lockheed's proposal for a space shuttle experiment. In July
1985, Acton found himself in orbit, operating solar telescopes
during eight days on the space shuttle Challenger. Escaping
the Earth's atmosphere is critical for making precise observations,
as atmospheric interference can clutter up data. "By
putting a telescope in space, every picture was perfect,"
Acton said. "And when you saw things happen, you had
to believe them and try to interpret them."
The
space experiments suggested that gas motions in the sun's
outer atmosphere are strong enough to push around the magnetic
field, Acton said. "This probably results in energy
storage in the corona," he said, which may contribute
to making the corona hotter than the visible surface of
the sun.
In addition
to his work on the X-ray experiment on YOHKOH, Acton has
been principal investigator on many NASA research programs,
including eight rocket experiments, all in the area of solar
X-ray studies.
Among
his many awards, Acton has received the 2000 Hale Prize
for long-term contribution to solar physics from the American
Astronautical Society, the 1993 NASA Exceptional Scientific
Achievement Medal, the 1988 Robert E. Gross Award for technical
excellence at Lockheed Corp. and the 1986 Spaceflight Achievement
Award of the American Astronautical Society. He also holds
an honorary doctorate from Montana State University.
Contact:
Dawn Levy, News Service (650) 725-1944; e-mail: dawnlevy@stanford.edu
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