Date Publication Category Author Illustration
07/11/1991 FE lester G

Experts urge caution during eclipse of sun

By Dave Lester


If you feel the need to go out of doors today, go right ahead; the weather will be fine. But under no circumstances are you to look at the sun, experts say.

That's good advice any day, but it's especially important today because a partial eclipse of the sun will be visible between 2:49 and 4:06 p.m.

A solar eclipse can be an awe-inspiring sight, but it should never be viewed directly. The cosmic convergence, which occurs when the moon passes between the sun and the earth, will be greatest at 3:28 p.m., when 16 percent of the sun's diameter is covered by the moon.

For people along a line through Hawaii, Baja, California and Mexico City, the event will bring the momentary darkness of a total eclipse, but for folks along a line between Pittsburgh, Murrysville, Greensburg and Kregar, a partial one is all they'll experience. It will seem like nothing more than a cloud passing over.

``With 16 percent, chances are you will not be able to notice it,'' says Stefano Casertano, a visiting professor in the Physics and Astronomy Department at the University of Pittsburgh.

He compared the change in light to what one would experience when wearing slightly tinted glasses.

He cautions that the sun at mid-afternoon is still quite high, quite bright and capable of damaging one's eyesight.

Scientists say that because the total eclipse will occur across a highly populated area, there is a danger that numerous cases of retinal damage could result among people glimpsing the scientific oddity directly.

Eric Canali of Buhl's Astronomy Resources says there's a very good chance that hundreds of people will damage their vision because the total eclipse will be long and will cover highly populated areas, including Mexico City, the largest urban center in North America.

Over a period of 3 hours and 25 minutes, an estimated 40 million people will observe it along a 9,000-mile-long band.

``The problem of course is that looking at the eclipse is liking having a laser burn of the retina,'' says Dr. King Hartman, a Greensburg ophthalmologist.

The macula, the central part of the retina, is damaged in such cases. ``If you get a burn of that area you have a central blind spot that's irreversible; it can't be fixed,'' says Hartman.

Ultraviolet sunglasses won't protect one from an eclipse or a laser burn either.

But while looking at the sun is discouraged, the eclipse is no reason to interrupt your routine.

A woman planning an outdoor birthday party for her daughter today called Pittsburgh's Buhl Science Center after several parents of the guests had expressed concern about whether they should send their kids because of the eclipse.

``We assured her that as long as the children don't look at the sun they would be in no more danger than any normal day,'' said Pam Pochapin, assistant director for marketing at Buhl.

Buhl, which cautions not to look at the sun with the naked eye, binoculars or telescope, will offer protected viewing of the eclipse from its rooftop observatory, weather permitting. The center will be open from 1 to 5 p.m. today with sky shows at 1:15 and 2 p.m.