Rare Solar Eclipse to Occur Sunday
NASAUpdated: May 14, 2012, 1:48 PM EDT
The annular solar eclipse as it appeared Jan. 15, 2010 in Qingdao, Shandong Province of China. During the annular eclipse, the moon passes directly in front of the sun, leaving a spectacular ring of fire.
On Sunday the sun is going to turn into a ring of fire. It's an annular solar eclipse, the first one in the United States in almost 18 years.
An annular eclipse occurs when the moon passes directly in front of the sun, but the lunar disk is not quite wide enough to cover the entire star. At maximum, the moon forms a "black hole" in the center of the sun.
For places such Medford, Oregon; Chico, California; Reno, Nevada; St. George, Utah; Albuquerque, New Mexico, and Lubbock, Texas; the afternoon sun will become a luminous ring.
Indian students and a tourist observe the rare annular solar eclipse on Jan. 15, 2010 at the central stadium of Thiruvananthapuram in Kerala, South India.
The "path of annularity" is a strip about 185 miles wide and thousands of miles long. It stretches from China and Japan, across the Pacific Ocean, to the middle of North America.
Outside of this relatively narrow zone, the eclipse will be partial. Observers almost everywhere west of the Mississippi will see a crescent-shaped sun as the moon passes by off-center.
"I like to compare different types of eclipses on a scale of 1 to 10 as visual spectacles," says NASA's leading eclipse expert, Fred Espenak of the Goddard Space Flight Center. "If a partial eclipse is a 5 then an annular eclipse is a 9."
This event should not be confused with a total eclipse. In a total eclipse, the moon covers the entire surface of the sun, bringing an eerie twilight to observers in the path of totality and revealing the sun's ghostly corona.
Espenak urges caution when looking directly at the eclipsed sun.
"The ring of sunlight during annularity is blindingly bright. Even though as much as 94 percent of the sun's disk will be covered, you still need to use a solar filter or some type of projection technique. A #14 welder's glass is a good choice. There are also many commercially available solar filters."
"One of the unique things about this eclipse for watchers in the USA is that the Sun will still be in deep partial eclipse at sunset, making for some great photographic opportunities," he said.. "In western Texas around Lubbock, the sun actually sets during the annular phase."
The next total eclipse in the United States will occur in 2017