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78 DISCOVERMAGAZINE.COM
ROEN KELLY/DISCOVER❯
OUR SUN MAY literally be young at heart. New
evidence suggests its core spins nearly four
times faster than its outer layers. This finding
sheds light on the initial conditions that formed
the sun, which spun much faster overall when it
was a young star.
The window into the sun’s core comes from
measuring elusive “gravity waves” that wash back
and forth through the solar interior like a sloshing
bathtub. (These are unrelated to cosmic gravitational
waves; for more on those, see page 13.) But the sunis a noisy place, and global pressure waves — more
prominent and numerous — mask the gravity waves.
Astronomer Eric Fossat and colleagues used
some 16 years of data from the orbiting Solar and
Heliospheric Observatory to study these clamoring
pressure waves, reporting their findings in August
in Astronomy & Astrophysics. By measuring tiny
changes in how long the pressure waves take to
race through the sun, scientists could reconstruct
the sloshing motion of the gravity waves, and
through them, scour the solar depths. — KOREY HAYNESPressure wave pathGravity wave pathQuickly
spinning
core
Quiet inner
envelopeTurbulent
outer layersSuper Solar Speeds
By studying the
sloshing of the sun’s
interior, astronomers
learned its core spins
much faster than its
outer layers.