Partial phases of May 20-21 solar eclipse will be cool, too

A wondrous annular or ring eclipse of the sun takes place on May 20, 2012 as seen from the southwestern U.S. – on May 21 according to calendars in Asia and Indonesia. For a comprehensive post about the annular eclipse, look here. This post will focus on the partial eclipse, which much of the world will be able to see. Given clear skies, all but the eastern part of North America can watch a partial eclipse of the sun in the afternoon hours on May 20. Much of eastern Asia and Indonesia will see the partial eclipse on the morning of May 21. Looking for eclipse times? Jump to the bottom of this post.

Map of May 20-21 partial and annular solar eclipse

Annular eclipse of the sun – China to Texas – on May 20 or May 21

As seen on the map above, a partial solar eclipse can be viewed today (May 20 or 21 if you’re west of the International Dateline) from almost all over the North Pacific Ocean, much of North America, Greenland, eastern Asia and parts of Indonesia. The partial eclipse can be seen from a wide area that goes as far north as the Arctic and as far south as Indonesia and Mexico. Meanwhile, only a small sliver of the globe will be in a position to see the annular eclipse (the narrow red band extending from southeast China to the southwestern United States).

In an annular – or ring – eclipse, the moon crosses directly in front of the sun, much as it does during a total solar eclipse. But, at an annular eclipse, the moon is too far away in its monthly orbit around Earth to appear large enough in our sky to cover the sun completely. An annular eclipse is a partial eclipse in the sense that the moon never blots out the sun completely. At no time can you gaze at an annular eclipse without protective solar filters to prevent damage to your eyes.

Photo of a partial eclipse of the sun

In a partial eclipse of the sun, the moon’s distance from Earth isn’t so important. A partial eclipse differs from an annular eclipse only in that the moon doesn’t line up with the sun quite so directly, as seen from your vantage point. 

The eclipse starts at sunrise on May 21, 2012 in Asia, travels eastward across the North Pacific Ocean and ends at sunset on May 20, 2012 in North America – nearly six hours later. Strange that the date goes backwards? Yes, as the shadow path moves along over Earth’s surface, it crosses the International Date line, going east. In fact, midway between Asia and North America, the greatest eclipse happens at local noon, very close to the International Date Line.

Always take utmost care of using proper eye protection when watching a partial or an annular solar eclipse. Because the eclipse happens in the late afternoon in North America, it’ll be to your advantage to find an unobstructed western horizon. The farther west you are in North America on the afternoon of May 20, the more of the eclipse that you will see. The US East Coast will miss out entirely because the sun sets before the eclipse even begins.

Keep in mind that both references give the times in Universal Time, so you need to convert from Universal Time into your time. For US time zones, subtract 7 hours for Pacific Daylight Time, 6 hours for Mountain Daylight Time, 5 hours for Central Daylight time and 4 hours for Eastern Daylight Time.