Of all the stars in the sky, our Sun is the only one near enough to show a sizable disk. Every clear day professional observatories worldwide and in space monitor its dynamic surface features at various wavelengths. One activity that almost any amateur can participate in is tracking sunspots on the Sun's visible surface (or photosphere). Sunspots often change rapidly and unpredictably from day to day; you never quite know what to expect. Long-term, consistent observations of their number, morphology (form), and distribution are valuable to researchers.

Of course, observing the Sun can be dangerous without the proper precautions. Looking directly at the Sun without adequate protective filters can result in irreversible eye damage. (See "Solar Filter Safety.") Of the many ways solar viewing can be conducted safely, I have chosen the screen-projection method. You don't look at the Sun directly; instead a telescope casts a magnified image of the Sun onto a screen.

Any flat, white, smooth screen works well, provided the surface is not glossy, which can result in glary reflections. For my projection setup I use poster paper (2-ply, 50 pounds) fastened to a wall near the doorway of my large garden shed. The telescope — a 10-inch f/6.5 Newtonian reflector with a 16-millimeter wide-angle Erfle eyepiece — is positioned about 4 feet from the screen. This setup projects an image of the solar disk 3 feet in diameter. (You can vary the size of the image by experimenting with various magnifications and projection distances.)

The detail seen this way can be quite extraordinary. With a clipboard, paper, and graphite pencil, I draw the sunspots freehand on an 8-inch-diameter circle inscribed on the paper, carefully noting their relative shapes, sizes, and positions based on the projected view.

From March 1987 to February 1991 I made daily white-light (unfiltered) solar observations using this projection method. I was able to record the rise of Solar Cycle 22 to maximum activity with 706 full-disk drawings of the Sun. They required about 414½ hours of drawing time at the screen.

You don't have to be an artist to become skilled in making accurate, detailed drawings of solar activity. But practice is the key for distinguishing the great diversity of sunspot forms and noting subtle changes in them. Observe until you feel confident and enjoy your solar viewing. Using sunspots as markers, you can follow the Sun's 27-day rotation period. Some sunspot groups reorganize themselves as they cross the solar disk, and these changes can become quite spectacular.

Observing Tips

Aiming your instrument at the Sun is as simple as finding the shortest shadow of the telescope tube. Thin clouds present no problem, and while it's true that atmospheric seeing is generally best in early morning, I have witnessed superb resolution in the afternoon! It all depends on your particular setup, location, and prevailing weather.

Use low powers only, because small, high-magnification eyepieces can be ruined by overheating in a very short time. You can also stop down the aperture to reduce the heat and light passing through the eyepiece.

Make sure the screen is exactly perpendicular to the eyepiece and the image is sharply focused on the screen. Wait until the solar disk is roughly centered on the screen before starting your drawing. A large disk will show the most detail, but it will appear faint since the light is spread out over a large area. You can increase contrast (and cut down on the heat buildup) by keeping the screen and the rest of the scope in shade.

A good way to tell the east-west direction is to leave the telescope stationary and let the image drift across the screen due to the Earth's rotation. Make a dot on a small sunspot, let it drift, dot it again, and draw a line between the two dots to record the exact east-west direction.

The west limb of the Sun is the leading or preceding one, and the east limb is following — two terms frequently used to describe celestial west and east on the Sun and planets. The north and south limbs can be identified by nudging the telescope slightly north; the Sun's image will move away from its north limb.