Observation Safety Precautions

Observation Safety Precautions

The total phase of a solar eclipse, when the sky is dark and the corona is visible around the Sun, is a beautiful sight. The best way to observe the event during these few brief minutes is simply to look directly at this glimmering halo in the sky. The corona is a million times fainter than the bright disk of the Sun; there is no danger of eye damage when looking directly at the corona or the prominences during totality. Binoculars may reveal even finer detail, but most observers agree that the naked eye is the best "instrument" for viewing the full glory of the event.

For about an hour before and after the total phase the Sun is only partially obscured. This is when it is dangerous to look directly at the Sun. Normally the Sun is too bright to look at anyway. But during the partial phases, the Sun does not appear as bright, and you may be tempted to look directly at it. DON'T DO IT! The danger of damaging your eyes does not depend on brightness. As long as any portion of the Sun's disk remains visible it can still cause eye damage.

The lenses of your eyes act as tiny magnifiers; if you look at the partially eclipsed Sun, its rays are focused on the retina of your eyes and can burn them. This is the same sort of thing that happens when you use a magnifying glass to focus the Sun to a pinpoint on paper or leaves to burn a hole in them. The only difference is that it is your eyes that would be burned. Part of the danger lies in the fact that the retina is not sensitive to pain; you wouldn't even feel it happening. But a retinal burn is permanent and irreversible, producing a blank spot in the most vital part of your field of vision.

Astronomers observe the sun directly through professionally manufactured optical filters that screen out the hazardous rays of the Sun. In recent years, manufacturers have also made available to consumers various forms of "eclipse viewers" that use the similar optical-grade filter material to give your a protected view of the crescent Sun during the partial phases.

And you're taking a big chance if you try to improvise your own filter. During the March 7, 1970, eclipse in the United States there were 145 reported cases of people who damaged their eyes by looking at the partially eclipsed Sun either directly or through sunglasses, exposed film, smoked glass, and the like. None of these homemade devices can be guaranteed safe. Play it smart and don't take any chances with your precious gift of vision.

** Material adapted from ECLIPSE by Bryan Brewer ($14.95 plus S&H). ECLIPSE Book Order Form. **

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