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| Space on May 15, 2012

For U.S. observers: Annular or ring eclipse on Sunday May 20

Annular eclipse on Sunday! Here’s the story ….

Those living along a narrow track from northern California to the Texas panhandle this Sunday (May 20, 2012) will have a chance to witness a special kind of eclipse of the sun. The sky won’t turn dark, and stars won’t pop into view, because this eclipse is essentially partial. At no time will the moon cover the sun completely, and thus you will need to use special filters, or an indirect viewing system, to see it. At mid-ecipse, though, if you’re equipped to observe, you’ll see an awesome sight. The outer rim of the sun’s body will appear as a brilliant ring completely encircling the black moon silhouette. Hence the name annular eclipse, from the Latin word annulus meaning ring.

Find out who can see the annular eclipse and when and how to see it: Here.

Looking for eclipse times? Jump to the bottom of this post.

Image credit: As the solar eclipse on May 20th progresses, its partial and annular phases will look very similar to this eclipse on May 10, 1994. Fred Espenak /SkyandTelescope.com

Americans are seeing the tail end of this eclipse. It begins at sunrise along the southern coast of China – across the International Dateline from us in the U.S. – where the date is May 21. The eclipse sweeps across Japan, and Tokyo residents – largest city in the world with a population of over 30 million – will be on the centerline. The eclipse then speeds across the North Pacific through much of the day before making landfall on the California-Oregon coast in the late afternoon of May 20, according to U.S. clocks and calendars.

Solar Eclipse Computer

The path of annularity runs across parts of southern Oregon, northern California, Nevada, Utah, Arizona, New Mexico, and the Texas panhandle. But those outside this path will see an eclipse, too. It’ll be an ordinary partial eclipse of the sun, whose depth will depend on how close you are to the central eclipse track.

Nearly all North America gets at least a partial eclipse on May 20th, with the moon taking a big bite out of the sun. The eclipse will still be in progress at sunset for much of the U.S., Canada, and Mexico. Image credit: SkyandTelescope.com

What to expect from North America. The sun will be moving down the afternoon sky when – with your solar filter or indirect view method – you perceive that a dark dent has began to intrude into one edge of the solar disk. As the eclipse progresses, depending on your location, the sun will eventually become a fat crescent – or, for the western half of the North America, a thin crescent.

What’s causing the dent? It’s the moon, at the new phase that day. Traveling along its monthly orbit around the Earth, the moon will pass directly in front of the sun’s disk. But it will be too far from Earth in its orbit to cover the sun completely. That’s why this eclipse is annular, instead of total.

Watch May 2012 solar eclipse at a National Park

Photo of January 15, 2010 annular or ring eclipse. Mottling, or granulation, caused by heat convection in the sun's atmosphere can be seen around the dark lunar disk. Credit & Copyright: Mikael Svalgaard: Mikael Svalgaard. Used with permission.

Click here to expand image above

People in the western U.S. will see the entire eclipse from beginning to end before sunset. In the central U.S., the sun will set while the eclipse is still in progress. The sky gurus at skyandtelescope.com advise:

Look for a weird and spectacular sunset scene just above the west-northwest horizon. Get your camera ready for a great photo opportunity!

The further east you are in the United States, the earlier in the eclipse the sun sets for your location. The U.S. East Coast misses out completely. There, the sun sets before the eclipse begins.

This will be the first “central” solar eclipse (meaning total or annular) to cross the United States since 1994.

What to watch for Remember, this is essentially a partial eclipse. The moon will be at apogee – farthest from Earth for the month of May 2012 – two weeks, or half an orbit, after the moon was a “supermoon” at perigee at full moon on May 5.

Find out how to watch the eclipse safely here. Image via Dionne Bunsha.

Only 88% of the sun’s surface area will be blocked during annularity. The visible surface of the sun – in a fiery ring around the moon – can literally blind you. So be sure to watch indirectly, or with special filters. Do not look at the sun directly without eye protection at any time during this eclipse.

The sky will not grow dark, but – if your sky is very clear – you should see that the sky is a darker, deeper blue than normal at mid-eclipse. 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.

How to watch the eclipse safely

Skyandtelescope.com points out:

Other things to look for during this eclipse include a silvery or metallic quality to the light around the time of annularity or when the sun is a thin crescent. Look for images of the crescent or ring sun being cast under leafy trees; small openings between leaves often make “pinhole cameras” projecting images of the sun on the ground.

Find the time of the eclipse for you with the U.S. Naval Observatory’s eclipse computer. This solar eclipse computer gives times in Universal Time. In case the eclipse is cut off by sunset (in the Western Hemisphere), or by sunrise (in the Eastern Hemisphere), this solar eclipse computer gives the sunset or sunrise time.

Or find the time the eclipse for you with a different tool, an solar eclipse path map from NASA. As with the solar eclipse computer above, the eclipse path map gives times in Universal Time. It’s a nice tool, too, although it doesn’t give the times for sunset or sunrise, which you probably need for this eclipse. You can create a custom sunrise-sunset calendar here.

How do I translate Universal Time into my time?

Bottom line: U.S. observers look here to find out about the annular or partial phases of the eclipse of the sun on Sunday, May 20, 2012.