Counting Sunspots on an Image of the Sun *
Abstract
Make a pinhole projector (see Measuring the Diameter of the Sun and the Moon). Use the pinhole to project an image of the Sun onto a wall or a piece of paper. Do you notice any dark spots on the projected image? Trace the projected image and count the dark spots. Use your pinhole projector to make images of the Sun at the same time of day for several consecutive days. How does the pattern of spots change? Can you use your data to figure out how fast the Sun rotates? Sunspot activity rises and falls with an 11-year cycle. At this writing (summer, 2006), sunspot activity is at a low point in the cycle, so you may not see any sunspots. You can use satellite images of the Sun for this project instead. See the Science Buddies project Using the Solar & Heliospheric Observatory Satellite (SOHO) to Determine the Rotation of the Sun. For another sunspot-related project, see: Sunspot Cycles. Important Safety Note: Never, ever look directly at the Sun. You can permanently damage your eyes.
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