Massive, long-lasting plasma flows 15 times the diameter of Earth transport heat from the sun’s depths to its surface, according to a study in the Dec. 6 Science. The finding supports a decades-old explanation of why the sun rotates fastest at its equator.
In the outermost 30 percent of the sun, known as the convective zone, rising plasma carries heat generated by nuclear fusion in the sun’s guts. Once at the surface, much of the plasma’s energy radiates into space; the cooler, denser plasma then sinks, driving further convection and creating circulating loops called convection cells. Some especially massive convective structures, called supergranules, can last up to 24 hours and have diameters greater than Earth’s.
In 1968, scientists theorized that even longer-lived and larger convection cells, big enough to span the entire convective zone, are necessary to maintain the fast rotation researchers had long observed around the sun’s equator; without such cells, the poles should rotate faster than the equator. Since then, scientists have sought such giant cells in telescopes’ observations of the sun.
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Source: Science News