A partial eclipse of the sun will darken Alaska skies Sunday afternoon.
In Anchorage, the eclipse will start at 3:17 p.m. (ADT) and end at 5:54 p.m. The event will be visible throughout Alaska, weather permitting (in Anchorage, the forecast is mostly cloudy), with slight variations in those times.
The solar eclipse will occur as the moon moves between the sun and the Earth, producing a shadow that, over the course of the day, will sweep across much of the Northern Hemisphere from the western Pacific to the U.S. Midwest.
At its fullest, 4:38 p.m. in Anchorage, the sun will appear as a crescent with the moon obscuring two-thirds of the solar disk. South of Alaska, viewers will be able to observe an "annular" effect, with the edge of the sun framing the moon in a "ring of fire."
Parts of the western United States and eastern Asia will be treated to the rare solar spectacle when the moon slides across the sun.
The solar spectacle will first be seen in eastern Asia around dawn Monday, local time. Weather permitting, millions of early risers in southern China, northern Taiwan and southeast Japan will be able to catch the ring eclipse.
Then, the late day sun (on Sunday in the U.S.) will transform into a glowing ring in southwest Oregon, Northern California, central Nevada, southern Utah, northern Arizona and New Mexico and finally the Texas Panhandle.
For 3 1/2 hours, the eclipse will follow an 8,500-mile path with the ring-of-fire phenomenon lasting as long as five minutes, depending on location.
Outside this narrow band, other parts of the U.S. and portions of Canada and Mexico will be treated to a partial eclipse. The Eastern Seaboard will be shut out but people can find online sites that plan to broadcast the event live.
It's impossible to know how many people plan to make an event of the ring-of-fire spectacle, the likes of which hasn't been seen in the continental U.S. for nearly two decades. One clue to demand might be found at the planetarium at the University of Nevada, Reno, which had to order another 10,000 solar viewing glasses after it sold out of them -- 17,000 pairs at $2 each -- last week.
NASA advises eclipse watchers never to look at the sun directly or through a camera, telescope or binoculars unless they are equipped with special filters. Sunglasses do not provide sufficient protection but welding masks with No. 14 glass may be used.
A safe and inexpensive method for viewing is to make a pinhole or small opening in a card. With your back to the sun, holding the card in front of you, you can see the crescent image of the sun projected on a surface in front of the card.
Here's one safe way to view the eclipse
From San Francisco's Exploratorium, a science museum: There are safe ways to view the sun during an eclipse. This one requires a long box (at least 6 feet long), a piece of aluminum foil, a pin, and a sheet of white paper. The length of the box is important. The longer the box, the bigger the pinhole image. To find the size of the image, multiply the length of the box by the number 0.0093.
For a box that is 1 meter long, the image will be 0.0093 meters (or 9.3 mm) in diameter.
If your box is 60 inches long, your solar image will be 60 x 0.0093 = 0.56 inches in diameter. If you can't find a long box or tube, you can tape together two or more boxes to make a longer one. We found that taping together two triangular UPS shipping tubes works well. If you do this, you must cut out the cardboard at the ends of the tube in the middle!
Find instructions and other options at Exploratorium.edu