Sky offers celestial gift with Christmas eclipse
December 21, 2000
If people wake up early enough Christmas morning, they will find a piece of the sun missing.
No, Santa didn’t give it away as a gift it is the final solar eclipse of the second millennium.
About 40 percent of the sun will be covered at the peak of the partial eclipse, when the moon casts a shadow as it passes between the Earth and sun, according to experts at the Sommers-Bausch Observatory at the University of Colorado, Boulder.
Viewing the eclipse at home is easy, according to Dr. Ron Danner, an optometrist in Craig.
“First and foremost, don’t look at the sun with your naked eyes,” he said. “The sun’s ultraviolet rays can burn the eye’s retina if you look directly at the eclipse without protection. The damaging radiation is still present during an eclipse, and that’s what burns the retina and creates a hole.”
The retina is the delicate lining at the back of the eye that contains layers of light-sensitive nerve cells used for seeing. Retinal burns cause permanent vision loss that cannot be repaired. Light-induced retinal injuries can happen without feeling any pain, and the effects of the injuries may not appear for several hours after the damage is done, Danner said.
“If you want to look at the sun during the eclipse, you need to purchase a pair of aluminized mylar cardboard eyeglasses made specifically for looking at the sun,” Keith Gleason, manager and laboratory coordinator at the Boulder observatory said.
Gleason said such glasses reflect more than 99.999 percent of the sun’s visible, infrared and ultraviolet light, dimming it enough for safe viewing. But, he said, make sure the glasses have been tested and determined to be safe for solar viewing. They can be purchased at hobby shops or stores that sell telescopes.
Do not look at the sun through a regular telescope unless it has a solar filter, officials say. Some observers prefer to watch the progress of the eclipse through a small portable telescope, which offers stability and is much less tiring to use for extended periods than binoculars. A telescope also provides more detail at higher powers.
When viewing an eclipse through binoculars, experts advise using common sense. Partial phases of the eclipse must be observed with solar filters over the lenses of the binoculars. Only when the Diamond Ring halo of the eclipse has faded is it safe to remove the filter. It is crucial to return to filtered viewing when the western edge of the moon’s silhouette begins to brighten. Binoculars are really two small telescopes mounted side-by-side.
It is also unsafe to view the eclipse through sunglasses, cameras, color film, black and white film, medical x-ray films with images on them, smoked glass, photographic neutral density filters and polarizing filters, according to the Colorado Optometric Association.
Examples of safe solar viewing filters include shade number 14 welder’s glasses, available from welding supply outlets, or special glasses, available through special manufacturers, constructed specifically for solar observation of DuPont MYLAR and polyester film, according to Jim Meyers, astronomy and math instructor at Colorado Northwestern Community College.
Danner said another safe way to observe the sun during the eclipse is to take two sheets of ordinary paper or thin cardboard and punch a hole in the middle of one of them. Once outside, turn your back to the sun, hold the paper with the hole next to your shoulder and flat toward the sun, while putting the second sheet in the shadow of the first. The sunlight will pass through the hole and form an image of the sun’s eclipse on the second sheet of paper.
The eclipse on Monday will last more than two hours beginning about 8:30 a.m. MST, Meyers said. Peak coverage will occur at about 9:45 a.m., when the sun will appear to be 40 percent covered by the moon. The eclipse will be completely finished at about 11:05 a.m.
An eclipse of the sun is rare, Meyers said, and only occurs with a new moon when the moon passes between the Earth and sun. The eclipse is actually the moon’s shadow sweeping across the surface of the planet. While a new moon occurs every 29.5 days, a solar eclipse is rather rare because the sun, moon and Earth must line up in essentially a straight line.
“Scaling it down a bit, think of the Earth as about the size of a standard desk globe and the moon orbiting the Earth 30 feet away as about the size of softball,” Gleason said. “It’s the shadow cast by the softball that must fall somewhere across the surface of the globe 30 feet away before an eclipse occurs.”
The moon typically passes as much as five degrees above or below the sun at new moon, Gleason said, which means its shadow usually misses Earth.
People in the United States, excluding Hawaii and Alaska, Canada, Mexico, Central America and the Caribbean will be able to see the partial eclipse on Christmas morning. An Internet site for learning more about eclipses is: http://www.mreclipse.com.