The first annular solar eclipse visible in the United States in nearly 18 years will occur on Sunday, May 20, 2012. Unless you are fortunate enough to live west of the Mississippi River you will not be able to see a partially-eclipsed sun, according to NASA.

In the United States, the path of annularity, or the path of the shadow, is only about 300 kilometers (186 miles) wide and stretches from southern Oregon and northern California to western Texas, crossing parts of Nevada, Utah, Arizona, Colorado and New Mexico. According to Space.com, about 6.6 million people live within the path.

The “path of annularity” is a strip about 300 km wide and thousands of km long.  It stretches from China and Japan, across the Pacific Ocean, to the middle of North America.  In the United States, the afternoon sun will become a luminous ring in places such as Medford, Oregon; Chico, California; Reno, Nevada; St. George, Utah; Albuquerque, New Mexico, and Lubbock, Texas.

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.

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.

Annular eclipses have a special charm all their own. During an annular eclipse, sunbeams turn into little rings of light.  The best place to see this is on the sun-dappled ground beneath a leafy tree. Hundreds of circular shadows can be found.

The Path for a full view of the eclipse. Outside of the path the view will be partial compared to inside the described grid.

Be careful when looking directly at the eclipsed sun, the ring of sunlight during annularity is blindingly bright.  Even though as much as 94% 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. In western Texas around Lubbock, the sun actually sets during the annular phase.

An annular eclipse is when the moon covers up most of the sun except for the sun’s outer fringe, leaving visible a ring of fire, or “annulus,” which is Latin for ring.

VIEW ECLIPSE ONLINE
If you’re east of the Mississippi River, don’t worry - the Slooh Space Camera is broadcasting the event live, using telescope feeds from Japan, California, Arizona and New Mexico. Slooh’s live feed begins at 5:30 p.m. EDT on Sunday. This would be the safest way to view the eclipse no matter where you live.