Sunspots form where intense magnetic field lines twist and poke up through the surface. These knotted fields shut down the normal flow, or convection, of hot plasma from the sun's interior to the surface, making the region cooler and darker than its surroundings.
- **Field Lines
Sunspots explode when the field lines twist to the point of snapping, like a rubber band wound too tightly. They link up again to form a new shape, but not before releasing enormous amounts of stored energy and hot gas into the sun's outer atmosphere, or corona.
- **Solar Flare
The resulting eruption, called a solar flare, heats the surrounding gas to 180 million degrees Fahrenheit. The explosion accelerates subatomic particles to near light-speed and spews radiation (mostly ultraviolet and gamma rays and x-rays) into space.
- **Plasma Burst
Flares are sometimes followed by coronal mass ejections (CMEs), in which billions of tons of the sun's plasma are flung into space en masse. These huge bubbles of matter travel relatively slowly (1,000 miles a second); even the fastest ones take a day or so to reach Earth.
- **Earth Impact
Eight minutes after a flare erupts, Earth's atmosphere absorbs the radiation pulse. This pulse produces extra ions and electrons, causing the atmosphere to puff out. The expanded atmosphere increases drag on satellites and degrades radio and GPS signals. But the worst is yet to come. Potentially more destructive than a flare's radiation pulse, CMEs boost the speed of the solar wind and create a shockwave of energetic protons. That shockwave distorts Earth's magnetic shield, and the protons stream down on the poles creating geomagnetic disturbances like the Northern Lights. The shockwave can also destroy the electronics in satellites.