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Safely Viewing Sunspots



Astronomers like Galileo learned more about sunspots by making daily observations and recording patterns over time. How did the early astronomers manage to look at the sun? One of the methods they figured out was projection. By using a telescope to project a smaller, dimmer image of the sun, they were able to study the sun at their leisure, with no risk to their eyes.

Galileo Portrait by Leoni

Galileo Galillei (1564-1642) was one of the greatest mathematicians and astronomers of all time. Born in Pisa on February 15, 1564, his work radically altered the scientific landscape of his time, setting the stage for much of modern science. By improving the telescope, and by using it to observe the heavens, Galileo amassed evidence for the Copernican idea that the earth revolves around the Sun, and that the earth is therefore not the center of the universe. His bold advocacy of the Copernican theory was a challenge to the accepted thought of the time, and ultimately Galileo was tried as a heretic by the Catholic Church. He was forced to recant his views, and he spent the last eight years of his life under house arrest.

Observe sunspots now
You can use this method to see sunspots for yourself. Be aware that viewing the Sun directly (either with the naked eye or with a telescope) is extremely dangerous. Galileo had to be careful to observe the Sun only very close to sunrise or sunset, but you can use this method to observe the Sun anytime.*

The safest practical way to see the sun is by lining up a telescope or binoculars on the sun, but instead of looking through the eyepiece, hold a sheet of white paper behind the eyepiece. The solar image is seen projected onto the paper, and you can safely look at it there.

You will need binoculars or a telescope, a camera tripod, a piece of paper or cardboard to create a shadow, a piece of white paper on a clipboard, or poster board, for a screen to project the image on to, and duct tape to hold all the parts in place.

1) Firmly fix the binoculars to a tripod. You can do this with duct tape.

2) Cut a shield out of cardboard and tape it to the front of the binoculars with the lenses sticking through holes that you cut.

Image series - how to construct a binocular sunspot projection viewer

3) Put the lens cap over one of the large binocular lenses or tape over one of the front lenses with duct tape (unless you want two images).

4) Use the duct tape to seal any holes that leak light past the cardboard.
Image series - how to use the binocular sunspot projection viewing set-up
5) Point the binoculars toward the sun while holding a piece of white cardboard about a foot behind the eyepiece.

6) It will take a little effort to find the sun. Once you do, you can focus the binoculars to bring the sun to a sharp image.

Warning: Be careful not to put your hand or anything flammable near the eyepiece! The concentrated sunlight focused there can cause a nasty burn or set something ablaze!

You should also give your binoculars a cooling break now and then by covering the front aperture. The eyepiece may become overheated and the lens elements may separate if you leave it on the sun too long.

Do your own spot check
Now you can watch a beautiful, bright, magnified image of the Sun. You will have to adjust the tripod now and then to account for the earth's rotation. You may be able to see sunspots. It depends on when in the "sunspot cycle" you decide to do this activity. You may want to jump to "The Sunspot Cycle" in the Modern Research section to learn more. This method also works great for watching partial eclipses of the sun.

In the next section, "Modern Research," you will discover how new technologies have added to our understanding of sunspots.

Until recently, we stated that Galilleo's blindness in later life was caused by his doing direct solar observations.  Although it is now known that this was not the case, please be careful anyway!

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