Most photographic images of the face of the sun show temporary, dark planet-sized regions called sunspots. These are caused by twisting magnetic fields rising from the interior of the sun and typically last for a few days or weeks. The dark spots are cooler than the rest of the sun, but still have a temperature of 4,000 degrees Celsius. These intensely active regions are often the source of strong magnetic outbursts and arc-like fountains of hot gas called solar flares which can be viewed on NASA websites. Dr. Martin Duncan
