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Frontiers
Listening to the Sun
January 1996
Solar physicists are putting a stethoscope up
to the Sun and hoping to hear a cough. If they are successful, their results
will answer long-standing questions about what is going on inside.
The NSF-funded, $20 million Global Oscillation Network Group, or GONG, took a
decade to build and started operations in October of 1995. GONG consists of six
solar observatories spaced around the Earth so that at least one of the observatories
always has the Sun in view.
"Despite the exquisite images we have of the Sun's surface, we know almost nothing
about its interior," John Leibacher told The New York Times. Leibacher
is chief scientist of the GONG project and solar physicist at the National Solar
Observatory. "Now we can use GONG to peer into the solar interior. We can use
what we learn about the Sun as a Rosetta stone to understand other stars. We'll
also learn more about how the Sun affects our own planet."
The rumblings of the Sun's interior do not travel through the vacuum of space,
and are, in any event, too deep for humans to hear. But the physicists are expecting
to "watch" the noise by studying oscillation patterns on the surface of the Sun.
GONG data should yield answers to basic questions, including: How does the Sun
derive power from hydrogen fusion? Why does the Sun have spots? And even provide
information on how much longer will the Sun sustain life on Earth?
"Until recently, it seemed impossible to resolve these questions by studying
the 98.5 percent of the solar system's mass that is contained within the Sun," John
Harvey of the National Solar Observatory wrote in Physics Today. But the
powerful sound waves recorded by GONG should reveal more of the Sun's secrets
than any other study so far, he says.
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