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TOEFL托福英語英語聽力原文：
On December 25, 2000, many people across North America received a rare Christmas treat when the moon passed in front of the sun resulting in a partial solar eclipse.
Solar eclipses occur when the moon passes between the Earth and the sun, and the moon's shadow covers part of the Earth, and a total solar eclipse takes place when the moon's shadow blocks out the sun entirely. What made this particular solar eclipse unique was that this event has occurred on December twenty-fifth only 30 times during the past 5000 years, the last time in 1954.
But people must be exceptionally careful when attempting to view a solar eclipse. Without taking precautionary measures, one can permanently damage the retina of the eye; however, there are several safe methods of witnessing this heavenly marvel.
First, you can view a solar eclipse by using eclipse safety glasses for filtering out the sun's harmful rays. They should be used when any part of the sun is visible.
Sunglasses can block out some of the sun's ultraviolet rays, but the results can be very deceptive. The eye's natural reaction to this darken state when wearing sunglasses is to make the pupil larger, which allows in more light and can intensify the damage to your eye.
You can watch an eclipse by projecting the sun's image on a piece of paper either by using a telescope, or easier yet, by creating a pinhole in a piece of paper and viewing the result on another piece of paper, thus called a pinhole projector.
Only during a total eclipse when the sun is completely and briefly covered can you watch the eclipse without eye protection. Even then, extreme caution should be taken.
In case you didn't catch this last spectacular eclipse on December twenty-fifth, 2000, there's no need to fret. Your posterity can record the next eclipse on Christmas in the year 2307, but only if they're visiting the west coast of Africa for the holidays.
