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Tiny explosions add up to heat corona

Solar nanoflares may explain high temperature far above sun’s surface

6:00am, April 29, 2015
the sun in UV

HEAT SEEKER  The EUNIS rocket split ultraviolet light from a region (white) of the sun into its component wavelengths (left, right), which revealed emissions from highly ionized atoms in a 10-million-degree plasma.

A relentless onslaught of tiny explosions buffet the solar atmosphere, researchers report. These eruptions, dubbed nanoflares, might help solve the long-standing riddle about why the sun’s corona is millions of degrees hotter than its surface.

“This is a real breakthrough to solving one of the most important problems in space science,” James Klimchuk, an astrophysicist at the NASA Goddard Space Flight Center in Greenbelt, Md., said at a news conference April 28.

The nanoflares rapidly heat the plasma in the corona, the sun’s outer atmosphere, to about 10 million degrees Celsius, says Klimchuk. The plasma then quickly cools to a relatively balmy 2 million degrees or so, still much warmer than the roughly 5,500-degree surface of the sun.

Each eruption belches out roughly the same amount of energy as a 10-megaton hydrogen bomb, Klimchuk says. While that amount of energy is enormous by

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