Voyage to the
Center of the Sun
the inner workings of the Sun were a mystery of cosmic proportions.
For many years, researchers have known that deep in the Sun's interior,
600 million tons of hydrogen fuse into helium every second, radiating
out the resulting energy. And while the mechanics of this conversion
have been described in theory, the Sun's interior has remained inaccessible.
Now, however, the Sun is being "opened," its internal structures
probed, and its inner dynamics surveyed by NSF-supported scientists
using investigative techniques-a branch of astronomy known as helioseismology.
study the Sun by analyzing the sound waves that travel through it.
Much as the waves produced by earthquakes and explosions roll through
the Earth, these solar sound waves pass through the Sun's gaseous
mass and set its surface pulsating like a drumhead. With six telescopes
set up around the Earth collecting data every minute, GONG scientists
are learning about the Sun's structure, dynamics, and magnetic field
by measuring and characterizing these pulsations.
Analysis of data from GONG and other sources shows that current
theories about the structure of the Sun need to be expanded. For
example, the convection zonethe region beneath the Sun's surface
where pockets of hot matter rise quickly and mix violently with
ambient materialis much larger than originally thought. Furthermore,
says Leibacher, the zone ends abruptly. "There is turbulent mixing
and then quiet. We can locate the discontinuity with great precision."
Some research teams are probing deeper and examining the Sun's core;
still others are addressing such topics as sunspotsplaces
of depressed temperature on the surface where the Sun's magnetic
field is particularly intense.
into the Sun's core came in the spring of 2000, when NSF-funded
researchers analyzing GONG data announced that they had discovered
a solar "heartbeat." That is, they'd found that some layers of gas
circulating below the sun's surface speed up and slow down in a
predictable pattern-about every sixteen months. This pattern appears
to be connected to the cycle of eruptions seen on the Sun's surface.
can cause significant disturbances in Earth's own magnetic field,
wreaking havoc with telecommunications and satellite systems. A
major breakthrough in the ability to forecast these so-called solar
storms came in the spring of 2000, when NSF-funded astrophysicists,
using ripples on the Sun's surface to probe its interior, developed
a technique to image explosive regions on the far side of the Sun.
Such images should provide early warnings of potentially disruptive
solar storms before they rotate towards Earth.
As our nearest
star, the Sun has always been at the forefront of astrophysics and
astronomy. (Astrophysicists study the physics of stellar phenomenon,
while astronomers have a broader job description-they observe and
explore all of the universe beyond Earth.) The more we learn about
the Sun, the more we understand about the structure and evolution
of stars and, by extension, of galaxies and the universe. The Sun
also is host to a family of nine planets and myriad asteroids and
cometary bodies. As we investigate the richness of outer space,
we often look for things that remind us of home.