After a decade-long nap, the sun is stirring, and experts are warning that magnetic flares could interfere with GPS signals on earth for hours, if not days. Cell-phone users may be annoyed, but the consequences could be serious for the shipping industry and the military. In February, NASA launched a satellite to measure solar activity. The goal: to one day predict the solar system's weather.
A version of this article appeared in the April 2010 issue of Fast Company magazine.