May 20th Annular Eclipse from Earth and Space

The above image is an X-ray view from space of the January 6, 2011 solar eclipse. The image was captured by the Hinode spacecraft. Image Credit: Hinode

This Sunday, May 20th, Earth will be treated to an annular solar eclipse. The event will be visible in the U.S. on a path from northwestern Texas through New Mexico, northeastern Arizona, southern Utah, Nevada, northern California and southwestern Oregon late in the day.

As the sun continues its path, the eclipse will then be visible over the North Pacific, in southern Japan and southern China on the morning of May 21.

An annular eclipse is similar to a total solar eclipse in that the moon lines up exactly with the sun. But in this case, the moon is close to apogee — the farthest point from Earth in its elliptical orbit around our planet — so that the moon is a bit too small to cover the solar disk completely. As a result, a ring of bright sunlight (some say a "ring of fire") will still blaze around the moon's circumference. At its peak, the eclipse will block about 94 percent of the sun's light. The event is described as an "annular" eclipse because the word comes from the Latin annulus, meaning "little ring."

Most of North America not in the totality footprint will still see a partial solar eclipse, without being treated to the ring of fire effect. Sadly, the East Coast will miss the event since the sun will have set before it begins. The eclipse will occur in the late afternoon or early evening of May 20 throughout North America, and May 21 for observers in Asia.

WARNING! Never view the sun directly with the naked eye or with any unfiltered optical device, such as binoculars or a telescope! If and when you view the sun, your first concern should always be eye safety. Serious eye damage — partial or total blindness — can result from even a brief glimpse.

One safe way to observe eclipses is to project an image of the sun through a telescope or binoculars onto a white screen — paper plates, walls and sidewalks all work nicely for this. If you're using a telescope, be sure that any small finder telescope is capped. If you're using binoculars, keep the cover on the tube which is not used.

Your projected image will be a circle of light. This is the disc of the sun. Adjust the distance between the screen and the telescope until the disk is about the size of a small paper plate. The image will probably be blurred, so focus your telescope until the circle becomes sharp. Using this method you can see considerable detail.

Pinhole projectors and certain types of solar filters can also provide a safe view of the sun. Pinhole projectors usually produce a small and unsatisfying image, but they are better than nothing if you don't have a telescope or binoculars.

Incidentally, with all of the solar observatories currently flying, you would think that some could take advantage of this rare event for some interesting observing. Well, as it turns out, the orbits for NASA's Solar Dynamics Observatory (SDO), NASA's Solar Terrestrial Relations Observatory (STEREO), and the joint ESA/NASA mission the Solar Heliospheric Observatory (SOHO) will not provide them with a view of the eclipse.

So what solar mission is left? Why, Hinode, of course! Hinode (Japanese, meaning "sunrise") is the joint JAXA/NASA mission to study the sun's magnetic field and better understand the mechanisms that power the solar atmosphere.

Hinode will observe the eclipse and provide images and movies that will be available on the NASA website at www.nasa.gov/sunearth. Due to Hinode's orbit around the Earth, Hinode will actually observe 4 separate partial eclipses." Scientists often use an eclipse to help calibrate the instruments on the telescope by focusing in on the edge of the moon as it crosses the sun and measuring how sharp it appears in the images. And as an added bonus, Hinode's X-ray Telescope will be able to provide images of the peaks and valleys of the lunar

After May 20th, the next solar eclipse will be the total solar eclipse of this November 13th. For more information on eclipses, visit this site: eclipse.gsfc.nasa.gov/eclipse.html

To find information about the time of any eclipse in your location: eclipse.gsfc.nasa.gov/JSEX/JSEX-index.html

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