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Background InformationAlthough the average distance from Earth to the sun is a whopping 149,600,000 km, careful observation from the Earth reveals a surprising array of visible features. The most conspicuous and best known feature is the sunspot.Sunspots were first observed by Chinese astronomers more than 2,800 years ago. With the invention of the modern optical telescope during the early 1600's, sunspot observations became more common. Galileo not only observed sunspots, but inferred from the movement of the sunspots that the sun rotated. He observed that sunspots occur in groups, and also noted that they occur in two bands above and below the sun's equator. It was not until 1843 that the next significant development towards understanding sunspots occurred. A German pharmacist, whose hobby was astronomy, discovered that sunspots occur in cycles: the number of sunspots increases, the decreases in an eleven year cycle. We now also know that the sun has a magnetic field much like the magnetic field that surrounds a bar magnet. This general magnetic field gradually reverses polarity during each sunspot cycle, like the north and south poles of a bar magnet are switched when the magnet is turned end over end. The result is that the sun has a 22 year magnetic cycle, as well as an eleven year sunspot cycle. Furthermore, sunspots themselves have strong magnetic fields that reverse after each eleven year cycle to conform to the 22 year magnetic cycle. In fact, sunspots are hugh magnetic field bundles that break through the surface of the sun. These magnetic fields create cooler, darker regions, which we see as sunspots. The dark center of the sunspot is called the "umbra." The light area around the spot is the "penumbra." Refer to Figure 10.1. Print at 92% for use in this Activity.Spots grow in clusters over several days or weeks, then gradually disappear. In the early years of a sunspot cycle, sunspots tend to be smaller and form at higher latitudes, both north and south. As the cycle proceeds toward the maximum number of sunspots in the eleven year cycle, the spots generally become larger and form closer to the equator. During the maximum period of the sunspot cycle, spots form at latitudes of 10 - 15o. As the number of sunspots increases during the sunspot cycle, so does solar activity. Sunspots are sources of solar flares, the most violent events in the solar system. In a matter of minutes, a large flare releases a million times more energy than the largest earthquake. |
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Sunspots and the resulting solar flares affect us here on Earth. In fact, the more we learn about
sunspots and solar flares, the greater their influence on Earth appears to be. Solar flares emit
radiation that includes x-rays and ultraviolet rays, charged particles called protons and electrons,
and powerful particles with no electric charge, called neutrons.
This radiation surge may damage electrical power systems, interfere with telecommunications, wreck high-tech ship navigation systems, harm an astronaut in space, or create the spectacular aurora (Northern and Southern lights). In 1989, Quebec suffered a blackout because a transformer was destroyed by the charged particles from a solar flare. If astronauts had been either outside a space station or on the Moon's surface in September, 1989, they would have received a lethal dose of radiation. Passengers flying on the Concorde supersonic jets would have received the equivalent of a chest x-ray without being aware of their exposure. Exposure to radiation from solar flares occurs without our being aware of it. Fortunately, a sudden surge in radiation on Earth caused by a solar flare may be predicted by an increase in the number and complexity of sunspots. Scientists at the Space Environment Laboratory in Boulder, Colorado conduct research in solar-terrestrial physics and develop techniques for forecasting solar activities. Also, they provide real-time monitoring and forecasting of solar activity. The Space Environment Services Center is the national and world warning center for disturbances that can affect people and equipment in the space environment. Although solar forecasters use sophisticated satellite and computer technology to improve space weather monitoring and analysis, researchers continue to observe sunspots using the same centuries old technique developed during the time of Galileo. Simply aim the telescope at the sun, project the magnified image onto a surface, and draw the spots. In this exercise, you will use techniques similar to those that solar observers use to record data based on sunspot observations at the Space Environment Laboratory in Boulder, Colorado. |
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Procedure - Part A
Note that groups of sunspots are identified together with only one number. Print at 92% for use in this Activity.
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Questions - Part A
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Procedure - Part B
Note that groups of sunspots are identified together with only one number. You will record sunspot information in Table 10.2 in much the same way that a solar observer records information for scientists to interpret. Print at 92% for use in this Activity.
(If your initial results do not agree with the observer's results, then try again...and again until you get it right.)
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Questions - Part B
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Conclusionsat the top of this web page and write your conclusions here. 
Figure 10.7. Conclusions Sheet Print at 92% for use in this Activity. |
