8月21日全美國有目共睹日全食 英語新聞

AZUZ (voice-over): Ten-second trivia:What happens when the moon passes between Earth and the sun and completely covers the sun?Total solar eclipse, annular solar eclipse, total lunar eclipse or penumbral lunar eclipse?Turn around, bright eyes. When this happens, you`re witnessing a total solar eclipse.(END VIDEO CLIP)AZUZ: And one of those is likely to be one of the first stories we cover after our summer break. Our new season begins on August 14th, and exactly a week after that, on August 21st, a total solar eclipse is expected to cross the continental U.S. In fact, everyone in North America could notice when the sun is at least partially covered by the moon. For those in the passing shadow, the landscape will appear darker, the temperature could drop.What`s being called the Great American Eclipse will last about an hour and a half from start to finish, and a couple of minutes when the sun is completely covered.Total solar eclipses aren`t that rare. They occur about once every 18 months. But the event this August is unique because it will be the first time in 99 years that a total solar eclipse cross over the U.S. from the Pacific to the Atlantic. Sky watchers from Oregon, to Wyoming, to Missouri, to South Carolina will see it if the weather is good.Some eclipse enthusiasts have had their hotels booked and their viewing parties planned for years.(BEGIN VIDEOTAPE)REPORTER (voice-over): Long ago, ancient cultures around the globe looked to the skies in shock and bewilderment. Many believed they were watching the sun being eaten by an animal, like a dog or a mythical dragon.Now we know there`s a more scientific explanation for one of nature`s most spectacular displays, the solar eclipse.(MUSIC)REPORTER: Watching as the moon blocks out the light from the sun, it can be hard to imagine the amazing cosmic coincidence taking place. The sun`s diameter is some 400 times larger than the moon`s, but it`s just the right distance away to appear the same size.For a couple of minutes when the sun and moon are perfectly aligned, the moon completely covers the sun`s disc. The sun`s atmosphere or corona can be seen in the dim light, along with stars and planets. This glowing atmosphere is much hotter than the surface of the sun, but no one is exactly sure why. It`s a question puzzling astronomers.This so-called totality only exists in a narrow band, where the moon`s shadow falls on the Earth. Outside this zone, some observers can see a partial eclipse, where it looks like a chunk has been taken out of the sun.
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