Solar flares are violent events that hurl billions of tons of gasses, electromagnetic radiation in the form of gamma rays and x-rays, and energetic nuclear particles (protons and electrons) into space (Fig. 5). Traveling at the speed of light, much of this radiation reaches the Earth in eight minutes. A large flare produces enough energy to supply a major city with electricity for 200 million years [6]. Originating near complex sunspot groups, flares are thought to occur when the magnetic field lines linking two sunspots becomes broken. Because of their relationship to sunspots, solar flares occur more frequently during periods of high sunspot activity.

While the Earth’s magnetic field serves as protection from most of the radiation released in a solar flare, one powerful enough can disrupt radio communications and wreak havoc with power grids. Such was the case in 1989, when a giant solar flare was responsible for knocking out major power grids in Quebec, Canada, causing widespread power outages. The high amount of ultraviolet radiation released in this event heated and expanded the Earth’s upper atmosphere, resulting in increased drag on satellites in low-Earth orbit. As the satellites dropped into a lower orbit and began traveling faster, communications with the spacecraft were temporarily lost.

Figure 5
Solar flare taken at Big Bear Solar Observatory.