Revealing the Sun's Complex Topography. (Solar Terrain)

Article excerpt

The sun is no smoothie. The sharpest images of the sun ever taken, released last week, show a rugged surface with gargantuan mesas and valleys formed of scalding gas.

The sun's surface is textured with short-lived structures, known as granules, each as big as Texas. "Up until now, we saw granules as flat pancakes with no apparent height or detailed structure," says lead researcher Tom Berger of Lockheed Martin in Sunnyvale, Calif. The new images, captured with the Swedish Solar Telescope in La Palma, Spain (SN: 11/16/02, p. 310), show some granular structures that are about 300 kilometers high, while the smallest discernible features are 70 kilometers across.

Berger and his colleagues presented the images in Laurel, Md., at the annual meeting of the American Astronomical Society's Solar Physics Division. By training the telescope on the edge of the sun, the researchers depicted the three-dimensional topographies of the granules, which last 6 to 10 minutes.

Some of these structures are molded by the sun's powerful magnetic field. By studying the features up close, solar physicists may learn how the magnetic field works and how it boosts or dims the sun's brightness as observed from Earth, Berger says. This is significant, he adds, because changes in brightness may affect Earth's long-term climate patterns.

The sun's magnetic activity waxes and wanes in an 11-year cycle. It's most frenzied during the so-called solar maximum, when the sun is mottled with dark sunspots--regions of intense magnetic force that lie like vast potholes on the sun's surface. …