By Richard Stenger CNN.com
Melinda Siskoff uses protective eyewear to
view the partial eclipse Monday in Rock Island, Illinois
(CNN) -- The
sun and moon put on a rare Christmas show as sky gazers across
much of North America witnessed a partial solar eclipse.
Such an event
won't happen again on Christmas Day for more than three centuries.
Jack Horkheimer,
executive director of the Miami Space Transit Planetarium, described
the event to CNN as a "cosmic ballet." Solar eclipses
only occur at new moon. Such events often seal young people's
decisions to go into astronomy as a career, Horkheimer said.
Many observers
fashioned primitive pinhole cameras to catch a glimpse of the
crescent sun. Others spied legions of eclipse silhouettes on the
ground as sunlight beamed through tiny breaks in the leaves of
trees and shrubs.
Sky
watchers in different latitudes watched "bites" of various
sizes removed from the sun as the moon passed in front of it,
leaving a darkened shadow on the Earth.
At the peak
of the eclipse, 12:23 p.m. EST, about 72 percent of the sun's
diameter appeared darkened from remote regions of northern Canada.
Peak eclipse times took place at slightly different times in other
parts of North America.
The eclipse
magnitude, or percent of the sun's diameter covered by the moon,
varied over the continental United States from more than 60 percent
in the northeast to under 20 percent in the extreme southwest.
Viewers in
parts of Central America and the Caribbean also caught a glimpse
of an even slighter eclipse.
The holiday
light show took place near the height of an 11-year cycle of sunspot
activity on the sun. The moon could be seen in contact with some
of the spots, according to Sky & Telescope magazine.
Astronomers
cautioned observers not to look directly at the sun, including
during a solar eclipse.
"The
eclipse itself if no more dangerous to view than the sun is on
any other day," said NASA scientist Fred Espenak in a statement.
"The only difference is that human curiosity impels some
people to stare directly at the sun during an eclipse and this
can cause permanent damage to your eyesight."
Eclipse diagram (Copyright 2000 Sky Publishing
Corp.)
Espenak advised eclipse watchers to use specially designed solar
filters on optical devices or even a simple pinhole camera, which
allows users to view a projected image of the sun.
Eclipses can
only happen when a new moon passes between the sun and Earth.
Observers can see the eclipse if the moon's shadow passes over
them as it sweeps across the planet.
The last solar
eclipse on December 25 occurred in 1954. It was an annular eclipse,
in which case the moon darkens most of the sun but leaves a "ring
of fire" around the edges.
The next total
solar eclipse will darken parts of South America and Africa on
June 21, 2001. Another Christmas Day solar eclipse, a partial
one, won't happen until 2307.
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