What Are Sun Spots?

Spots that appear on the sun are not truly spots on a solid surface in the sense that we understand them. Since scientists believe the sun is a massive collection of burning gases (at least on the extreme outside) the spots are actually areas that have a lower temperature. They are so large that people standing on the Earth can see them without using a telescope.

Sunspots differ in temperature by as much as 1000 degrees (or more) and indicate a high level of magnetic action. They appear darker than the rest of the sun’s surface, but the light would still be too bright to look at from close range. A sunspot is cool in comparison to the rest of the surface because, in the sunspot area, hotter gas from the interior of the sun does not move to the surface. Activity around sunspots is sometimes referred to as “solar storms,” since the movement of gases is so violent in these areas.

These interesting phenomena occur in cycles that last approximately 11 years (give or take). In fact, astronomers have numbered these cycles since the time they first observed regular patterns. According to encyclopedia information a new cycle begins when the number of spots on average is higher (at a new magnetic polarity) than the number of spots at the old polarity level. According to most measurements, 2009 is supposed to be the year a new cycle begins.

There are other activities on the surface of the sun that have different causes. These include loops and flares that spring up in the area of sunspots. With new, strong telescopes, scientists have observed this same type of activity on the surface of other stars that are much farther from Earth. History records that the legendary scientist Galileo was the first to observe and then record his ideas about sunspots. He reportedly used an early telescope to make his observations.

Observations over the years have revealed that sunspots are the size of some of the planets in the solar system, which gives us an idea how massive the sun is. These huge spots appear to be very tiny on the massive star that provides us heat and light. Some have compared the appearance of light in a sunspot to the full moon we experience here on Earth. Of course, the moon appears bright only because of reflected light from the sun.

One of the details that scientists have uncovered about sunspots is the variance of light or amount of heat in one sunspot. A penumbra is the area at the outer edge of a sunspot that appears brighter. The umbra, on the other hand, appears a bit darker and is the area closer to the center of the sunspot.

The basic knowledge of sunspots includes: last for several days or even a few weeks or months; the number of sunspots varies depending on the current magnetic activity; sunspot cycles last approximately 11 years. While astronomers have learned a lot about the surface activity of the sun, there is still much to be discovered about this star that is millions of miles from Earth.

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