Sunday's annular solar eclipse in which the Moon blocks out most of the Sun leaving a ring of light around its circumference will be visible in parts of eight western states in which an estimated 6.6 million Americans live.
An annular eclipse occurs when the Moon passes between the Earth and the Sun close to apogee, the point that marks the Moon's farthest distance from the Earth. The eclipse is called an annular eclipse because the Moon does not completely cover the Sun, and it leaves a "ring of fire" around the Moon.
The word "annular" is from Latin "annulus" meaning ring.
The eclipse will occur in the afternoon and early evening on Sunday (May 20).
For observers in favorable locations, it promises a spectacular sight. It will be best seen from a narrow band on the Earth's surface where the shadow of the Moon falls. The full "ring of fire" spectacle should be visible from much of Asia, the Pacific region and parts of western North America. According to Space.com, the band stretches at dawn in southern China, across the Pacific Ocean, through south of Alaska to the Pacific coast near the California-Oregon border and ends near Lubbock, Texas, at sunset.
Weather.com reports it will be visible in parts of southwest Oregon and northern California to New Mexico and western Texas.
According to EarthSky.org, the eclipse will pass over Japan, with Tokyo on its centerline, and then across the North Pacific to California-Oregon coast in the late afternoon of May 20. The path of the annularity will run across parts of southern Oregon, northern California, Nevada, Utah, Arizona, New Mexico, and the Texas panhandle, with those outside this path seeing only a partial eclipse.
Weather.com reports observers almost everywhere west of the Mississippi will see a crescent-shaped Sun as the Moon passes by off-center. Partial phases of the eclipse will be visible over most of western North America.
The "Ring of Fire," according to AccuWeather.com, will create a remarkable display for roughly 3 to 4 minutes over cities such as Medford, Ore., Redding, Calif., Reno, Nev., Cedar City, Utah, Albuquerque, N.M., and Lubbock, Texas.
Viewers of the eclipse in North America are advised to observe the eclipse from a site with a good western horizon because the eclipse will occur late in the day. Viewers are also advised to prepare for the possibility of inclement weather because of obscuring clouds. You may consult the Clear Sky Chart for places closest to your location with clear sky for unimpeded view of the eclipse.
Weather.com, however, reports that the majority of areas in the path of the eclipse will have clear sky with two possible exceptions: "The tail end of a frontal boundary and an upslope flow could bring some thunderstorms and cloud cover to eastern New Mexico and western Texas." Meteorologists are also watching to see if an approaching frontal system off the Northwest coast will bring clouds to southwest Oregon and northwest California.
Space.com advises that because the eclipse is occurring a few months ahead of summer solstice, the Sun will be setting quite far north of due west. Views are advised to check the Sun's setting point a day or two beforehand to verify that trees or buildings do not block view
Observation locationsSpace.com details the following observing options for viewers to choose from:
Position near the center of the eclipse
Position just inside the northern or southern limit of the eclipse track.
Position near the sunset point of the eclipse track.
From the position near the center of the eclipse, viewers will observe a gradually increasing partial solar eclipse until the Moon is almost at the middle of the Sun. The viewer will see a lopsided "ring of fire" with one side shinning brighter than the other. At mid-eclipse, the ring will appear as a perfect ring, with the Moon's dark disk about 94.4 percent of the apparent diameter of the Sun behind it, Space.com reports. After mid-eclipse, the ring will appear lopsided again until the silhouette of the Moon touches the other side of the Sun.
The main advantage of the "near the center of the eclipse" position over the two others is that the duration of the eclipse is longest. According to Space.com, the "annularity" will last about 4 minutes 47 seconds in the town of Requa at the Pacific Coast in northern California. According to Space.com, the appearance of the perfect ring will last only about 90 seconds.
To avoid serious damage to the eyes and even blindness, never look directly at the eclipse with the naked eyes, telescope or binoculars. Fit special or solar filters over your equipment. Space.com recommends No.14 welder's glass because it is denser than the standard No.12. The glass is available at specialized welder's supply stores
Viewers may also buy "solar shades" from telescope stores. Viewers are advised not to use any regular sunglasses or any domestic sun-shade facility.
The annular eclipse may also be viewed indirectly with the projection method. A telescope or one side of a binoculars may be used to project a magnified image of the Sun on a shaded white piece of cardboard
As the Moon moves across the face of the Sun, it may encounter features such as sunspot that provide photo opportunities. You may use you camera to take photos of the Sun through your telescope or binoculars. A camera adapter will be required to do this. An annular eclipse gives skywatchers extended photo opportunities because compared to other type of eclipses it takes a long time to pass.
Space.com suggests comparing your times of the four contacts with those predicted. The first contact is when the edge of the Moon first touches the edge of the Sun. Second contact is when the disk of the Moon is wholly in front of the Sun. Third contact is when the Moon touches the edge of the Sun as it begins to pass away from the Sun, and Fourth contact is when the Moon is completely clear of the Sun.
EarthSky.org explains the sky will not grow dark, but you would see that the sky has a darker, deeper hue of blue than normal at mid-eclipse.
EarthSky.org also instructs viewers to look for the brightest planet, Venus, at mid-eclipse. "It’ll be shining east of the sun by about two fist-widths at arm’s length. Jupiter and Mercury are up there, too, but they are fainter and so will be harder to see. They’re on the other side of the sun by about a quarter and a third as far, respectively."
EarthSky.org suggests that skywatchers look for images of the crescent or ring Sun being cast under leafy trees. The website explains that small openings between leaves often make "pinhole cameras" that project images of the Sun on the ground.