Northern Californians are in for a solar treat as the moon's shadow sweeps across the Earth to create an annular eclipse of the sun on, appropriately, Sunday, May 20. Unlike a total eclipse, however, the rim of the sun still will be visible around the moon, which means people hoping to catch a glimpse of the early evening phenomenon must exercise caution to avoid serious eye injury.
"This eclipse can be fun, but it does come with a bit of warning," said Ivan Schwab, professor of ophthalmology and a specialist in cornea and external eye diseases at the UC Davis Eye Center in Sacramento. "It is never safe to view the sun partially eclipsed without protective eye wear. Just because the sun appears dim and you don't feel discomfort doesn't mean that your eyes are safe. Special eclipse glasses must be worn to safely view this solar event."
Solar radiation that reaches Earth can be transmitted by tissues in the eye to the light-sensitive retina at the back of the eye. Improper viewing of the sun during an eclipse can cause retinal burns, or what is known as "eclipse blindness, and potentially cause permanent damage. Inexpensive solar eclipse viewing glasses can be found online. Student science clubs at local universities and high schools also may have the safety glasses available.
"Eclipses are like the birth of a baby," said Schwab. "They come with much anticipation and excitement, are all different, and the differences are important and may require special equipment. In the case of this annular eclipse, do not attempt to view the sun through pinhole glasses, regular sunglasses or other makeshift glasses. You can't afford to play with the potential of visual damage," he warned.
Keeping safe viewing in mind, the best views of Sunday's event will be north of Sacramento, closer to Redding. The eclipse begins about 5:30 p.m. Pacific Time as the moon starts moving in front of the sun. The complete annular eclipse occurs about 6:20 p.m. and will last approximately four minutes. To see the exact the pathway of the eclipse and the best viewing locations as it moves across the Earth, visit the NASA web site.