Dec 14, 2000

Christmas Eclipse




On Christmas Day, 2000, alert sky watchers across North America can enjoy a partial solar eclipse.


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December 14, 2000 -- Holiday revelers who happen to find solar filters under their Christmas tree this year can put the unusual gift to immediate use. That's because a solar eclipse is coming on Christmas Day, 2000. Across parts of North America, the winter landscape will briefly assume an eerie cast, and cooler-than-usual winds might swirl as the New Moon glides across the face of the Yuletide Sun.


But don't expect the lights to go out completely. This eclipse will be a partial one -- at most 72% of the Sun's diameter will be occulted by the Moon.

Above: Photographer Thomas Colin captured this dramatic sunrise on August 11, 1999, when the partially eclipsed Sun appeared above a cloudy Quebec horizon. [more information]




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Sky watchers who live in the continental United States, Canada, Mexico, or the Caribbean can enjoy the show, but only if they're careful. Looking directly at the Sun this Christmas can inflict blindness just as surely as it would on any other day. A partially-eclipsed Sun is still very bright.

"Extreme care must be taken when watching the eclipse," writes Fred Espenak of the Goddard Space Flight Center. "Never look at the Sun with the naked eye or through any optical device such as [unfiltered] telescopes or binoculars. Human curiosity impels some people to stare directly at the Sun during an eclipse and this can cause permanent damage to your eyesight."

Fortunately, there are safe ways to view an eclipse. Chief among them is projecting an image of the Sun onto a screen through a properly shielded telescope or a properly shielded pair of binoculars. Sky & Telescope's web page "How to Watch a Partial Solar Eclipse Safely" explains such techniques.


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Above: In this diagram from Sky & Telescope (copyright 2000, all rights reserved) little crescents show how the Sun will look at mid-eclipse in various North American cities on Christmas Day. Click on image for larger view, which will also show the local times of maximum eclipse. [more information from Sky & Telescope]

Residents of the Pacific northwest and western Canada will have to dash outside just after sunrise for best viewing. The eclipse will already be in progress as the Sun peaks above the eastern horizon -- a potentially dramatic sight. [photo tips]

Drowsy sky watchers east of the Rocky Mountains can sleep a bit longer, provided their kids will allow it on Christmas Day. The maximum eclipse over Denver won't happen until nearly 10 a.m. local time, while people on the Atlantic coast can wait until after lunch to see the show. Fred Espenak has tabulated eclipse viewing times for cities in the United States, Canada, and Latin America.


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Right: This unique eclipse animation, courtesy of Dr. Andrew Sinclair, shows the motion of the Moon's shadow across Earth's surface during the Dec. 25th eclipse.

The biggest "dent" in the Sun will appear at 1723 Universal Time (12:23 EST) on Dec. 25th when 72% of the Sun's diameter will be covered by the Moon. Unfortunately, only the residents of Baffin Island in northern Canada will see so much of the Sun obscured. Elsewhere, the eclipse magnitude will vary from ~60% in the northeastern USA to less than 20% in the far southwest. (Eclipse magnitude is the percent of the Sun's diameter covered by the Moon.)


Observers in those northeastern regions where the eclipse magnitude will be greatest might note a subtle change in the cast of sunlight across the landscape. Elsewhere, the day will appear as brightly lit as usual.

And if you happen to spend a little too long opening gifts on Christmas morning, and miss the eclipse, don't despair! There are at least two solar eclipses every year and --on rare occasions-- as many as five. Visit NASA's Five Millennium Catalog of Solar Eclipses to find out when the next eclipse will be visible from your part of the world. Another one may be right around the corner!


Web Links


Solar Eclipses for Beginners -- from

The Last Eclipse of the 2nd Millennium! -- NASA/GSFC press release

Partial Solar Eclipse -- Sky & Telescope article


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