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In the early
17th century, Galileo
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used
sunspots to determine that
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the Sun
rotates in about 27
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days. We now know that the
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Sun is not a
solid body. Its
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equatorial
rotation period rate is
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about 25
days, while the polar
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period is
about 35 days.
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Color code:
Red is faster, blue is slower.
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Helioseismology
tell us that
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this
“differential rotation” extends
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far below the surface.
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