Sun spots

Have you ever seen someone with a lot of freckles? Freckles are small dark spots on the skin. Sometimes people get freckles when they spend time outdoors in direct sunlight.

Strangely enough, the sun has “freckles”, too. These dark places on the sun’s surface are called sunspots. You should not try to see these spots because your eyes can be damaged by looking directly at the sun. But astronomers can safely observe sunspots by looking through their telescopes.

A sunspot usually lasts for a day or two. It is not really a “spot” at all but a hole. The surface of the sun is made of very hot gasses. In some places the gases whirl around and get cooler. These cooler whirlpools are darker than the rest of the surface and look like spots.

Scientists have learned that sunspots usually occur in eleven- year – old cycles. At the beginning and end of each cycle there are very few sunspots. But in the middle years of a cycle there may be hundreds of sunspots.

There may be a link between sunspots and life on the Earth. For instance, trees seem to grow faster during the years when there are more sunspots. About three hundred years ago sunspots practically disappeared for a period of seventy years. No one knows why. During those same years something changed the normal growth of trees. Scientists can see the pattern of a tree’s growth by examining the annual rings in the wood when the tree is cut down. The rings of very old trees show very little growth between 1645 and 1715 – the years the sunspots disappeared.