Amazing Photos of the Sun

NASA's 3-D Photos of the Sun
SST / Royal Swedish Academy of Sciences

The dark areas are caused by intense magnetic activity that creates regions of reduced surface temperature. Sunspots expand and contract as they travel at a few hundred miles per second across the surface of the sun. They can be as large as 50,000 miles (80,000 km) in diameter, making them at times visible to the naked eye from Earth.

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