Sunspots & Their Effects on Earth

Sunspots Explained

• Although it looks like it from our perspective, the sun isn't a flawless glowing surface --- its color and heat is broken, at intervals, by the phenomenon of the sunspot. Sunspots are cooler regions of the sun, although they're still many thousands of degrees; their darker color only really shows up in contrast to the surrounding areas. They're caused by magnetic activity; when this magnetism slows down convention inside a star, less heat is brought to the surface and that small area (which is often still larger than the Earth) is rendered slightly cooler.

The Solar Cycle

• The number of sunspots visible on the surface of the sun isn't constant, nor is it completely random. The numbers vary over a period of between nine and 14 years, generally averaging around 11. At "solar maximum," the greatest number of sunspots can be observed, with hundreds of sunspots visible. At "solar minimum," the lowest point of the cycle, sunspots may disappear entirely for days at a time. Cycles also vary in strength --- the number of sunspots at solar maximum during one cycle may still be much smaller than the number of sunspots at solar maximum during another cycle.

Sunspot Effects

• Counterintuitively, when more sunspots are visible the sun is actually brighter --- the area surrounding a spot is so bright that it outweighs the cooler center of that spot. Sunspots, as magnetic activity, are also associated with other solar activity. Solar flares, for instance, spring up around sunspots, jetting intense amounts of energy outwards in the form of ionized gasses and radiation that spreads across the entirety of the electromagnetic spectrum. Coronal mass ejections are a much large phenomenon, with the sun flinging tens of millions of tons of matter out into space.

Sunspots and Earth

• Some effects of sunspots are without controversy: solar flares, for example, are more common when there are large amounts of sunspots, and generate large amounts of radiation that cause hazards for astronauts, brilliant aurorae and disruption to satellites and electrical equipment. More controversially, the fact that the sun becomes cooler when there are fewer sunspots may lead to cooler temperatures on Earth: the "Maunder Minimum," a period of time between 1645 and 1715 with very low sunspot activity, correlates to the coldest part of the "Little Ice Age," a time in Earth's recent history marked by cold summers and bitter winters.