While no direct link between sunspots and Earthly events, such as volatile stock markets, has ever been found, extremes in sunspot activity have been correlated in some cases with climate changes on Earth. For example, the “Maunder minimum,” a period of exceptionally low sunspot numbers in the 16th century, does coincide with a time of unusually low temperatures around the world — the so-called “Little Ice Age.”
A more direct case can be made, however, for solar flares, which often cause quite a bit of terrestrial turmoil. These brief, intense explosions of high-energy particles and radiation from the Sun have been responsible at various times for frying the circuitry of artificial satellites, disrupting radio and television broadcasts, and bringing down the entire power grid of Quebec. Because of their proximity to the northern magnetic pole, which guides the particle streams down to Earth over the Arctic, Canada and the United States find themselves particularly susceptible to solar-flare disruptions. Flares also trigger brighter, more extensive aurorae that may be visible from the southern United States. A considerable amount of effort has been directed toward predicting and detecting these events.
For the person on the street, however, solar flares and sunspots generally have little impact. It’s only the rare, extremely large flare that causes extensive electronic disruptions.