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发表于 2014-10-20 16:51
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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.
Key Vocabulary [Top]
treat (noun): a special experience
- Going to Disneyland for Christmas will be a real treat for the kids.
partial (adjective): incomplete
- The win for the team was only a partial victory since their starting player was injured and will be unable to compete for the next few games.
exceptionally (adjective): extremely
- The boy is exceptionally bright for his age.
precautionary (adjective): taken in advance to protect against possible danger
- As a precautionary step, I believe we should check all of the equipment again to make sure it is working properly.
measures (noun): steps, methods, or procedures
- The astronauts took drastic measures to prevent a collision with the oncoming asteroid.
witness (verb): watch or view
- I'm not sure if we will be able to witness the lunar eclipse because the skies are cloudy.
deceptive (deceive) (adjective, also verb): mislead, often deliberately or inadvertently
- The stars at times seem to twinkle in the night sky, but this perception can be somewhat deceptive. Actually, the star light passing through the atmosphere creates this effect.
intensify (verb): to make stronger
- Over the past several weeks, solar flare activity has intensified disrupting radio transmissions in some parts of the world.
fret (verb): to worry unnecessarily of excessively, or be unhappy
- The boy fretted over losing his favorite toy. |
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发表于 2014-10-22 10:55
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