A Sunspot Up Close
5/10/1998 
False color picture of a sunspot taken with the National Solar Observatory's Vacuum Tower Telescope (now redesignated as the Richard B. Dunn Solar Telescope) at the Sacramento Peak Observatory, showing features on a scale of about 100 km.
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Credit: Vacuum Tower Telescope, NSO, NOAO  

Sometimes, small regions of the Sun appear unusually dark. Visible above is a close-up picture of a sunspot, a depression on the Sun's face that is slightly cooler and less luminous than the rest of the Sun. The Sun's complex magnetic field creates this cool region by inhibiting hot material from entering the spot. Sunspots can be larger than the Earth and typically last for only a few days. This high-resolution picture also shows clearly that the Sun's face is a bubbling sea of separate cells of hot gas. These cells are known as granules. A solar granule is about 1000 kilometers across and lasts about 10 minutes. After that, many granules end up exploding.  
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