Astronomy Picture of the Day

Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.

2000 May 22
See Explanation.  Clicking on the picture will download 
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Light Bridges on the Sun
Credit: G. Scharmer, L. Rouppe van der Voort (KVA) et al., SVST

Explanation: 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.

Tomorrow's picture: Big Ball of Stars M4

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Authors & editors: Robert Nemiroff (MTU) & Jerry Bonnell (USRA)
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/GSFC
& Michigan Tech. U.