Newspaper article The Christian Science Monitor

Scientists Begin to Unravel a Stubborn Solar Mystery ; New Research Could Also Shed Light on Phenomena That Knock out Satellites

Newspaper article The Christian Science Monitor

Scientists Begin to Unravel a Stubborn Solar Mystery ; New Research Could Also Shed Light on Phenomena That Knock out Satellites

Article excerpt

To astronomers, one of the sun's most puzzling mysteries has centered on why the star, fiercely hot at its core, cools with distance, only to have temperatures in its extended outer atmosphere soar again.

"It's as though you walk away from a campfire, get cooler and cooler, then you start getting hotter again," says John Leibacher, an astronomer at the National Solar Observatory in Tucson, Ariz.

In research to be published next month, astronomers at Lockheed Martin's Solar and Astrophysics Laboratory in Palo Alto, Calif., have taken a crucial step toward solving the mystery. In the process, some scientists say, the team's work may shed light on enormous outbursts of charged particles that can wreak havoc on satellites, trigger power blackouts on Earth, and send ribbons of blue, green, and red aurora weaving through the night skies.

While they don't yet know the reason for the strange temperature pattern, their research has given scientists a new understanding of where the sun's corona is heated - toppling long-held theories and getting astronomers closer to answers.

"This overturns a picture basic to the field for about 30 years," says Craig DeForest, an astrophysicist at the Southwest Research Institute in Boulder, Colo. "This is important to all aspects of the field."

Until now, conventional wisdom had held that the corona was like a thin gaseous atmosphere, heated uniformly.

This led to at least 10 competing explanations for the high temperatures in the sun's corona. (The sun's core burns at about 27 million degrees F., its surface falls to about 10,000 degrees, then the corona - stretching millions of miles into space - rockets back up to between 1.8 million and 9 million degrees.)

But the Lockheed Martin team, using data from NASA's TRACE satellite, found that the corona is heated unevenly from below, as if by enormous numbers of gas jets that emerge from beneath the corona.

"To solve the [heating] puzzle," says Lockheed astronomer Markus Aschwanden, "you first have to know where the corona is heated, then you can sort out the physical mechanisms. We have identified where the heating occurs. …

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