Sunday, April 29, 2012

May 20th Annular Solar Eclipse: East Asia, North Pacific, North America

 May  20th will see an annular eclipse of the Sun. These happen when the Earth, Moon and Sun are exactly in line and the Moon partly blocks out the light of the Sun. Unlike total eclipses, when the whole of the bright solar surface (the photosphere) is obscured, the Moon is too far away from the Earth to completely cover the Sun, so a bright ring or annulus is left around the lunar silhouette, hence the term annular eclipse.

The annular solar eclipse of 3 October 2005. 
Credit: Sancho Panza 

This eclipse is visible along a narrow track running from southern China (including Hong Kong), Taiwan (including T’aipei) Japan (including Osaka and Tokyo), the northern Pacific Ocean and the south-western United States including Albuquerque and Santa Fe. The maximum duration of the eclipse is 5 minutes and 40 seconds, as seen from just south of the Aleutian Islands.

Outside of this track, observers across central and east Asia, most of North America and Greenland will see a partial eclipse of varying duration, where the Sun is partly obscured but without the ring effect.

Although annular eclipses of the Sun are spectacular events, unlike total eclipses they should NOT be viewed with the unaided eye. Looking at the Sun without appropriate protection can cause serious and permanent damage to the eyes.
The eclipse can be safely studied using purpose-designed solar filters available from reputable astronomical suppliers. Without these, the only safe ways to observe the Sun are to use a pinhole or telescope to PROJECT the Sun’s image onto card or to look at the natural dappled images under trees.

Eclipses online: information on eclipses around the world

NASA: Annular solar eclipse of 20 May 2012

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