Light Bridges on the Sun.

Bridges the length of a planet can form on the Sun in a matter of hours. Known as light bridges , these structures may form as large sunspot groups decay. Above , one of the sharpest photographs of the Sun ever taken shows two such light bridges that appeared late last month. The 5000-kilometer long bridges connect moderately dark penumbral regions across the cool abyss of two dark sunspot umbras . A movie shows that material tends more to rise from below and fall rather than to cross the light bridges. Bright bubbling granules surround the sunspot group . The impressive details on this recently released picture from the Swedish Solar Vacuum Telescope were made possible by new adaptive optics that correct for the blurring of the Earth's atmosphere . What eventually became of the light bridges ? As days progressed, the bridge region expanded to fill the void as the sunspots moved apart and decayed.