54 本周四将出现本世纪首次日蚀-英语课

时间：2019-01-31 作者：英语课 分类：VOA2001-国际风云（1）

英语课

Thursday's Solar Eclipse Should Provide Dramatic View

David McAlary

Washington

20 Jun 2001 02:44 UTC

The first 1)solar eclipse of the new millenium occurs Thursday, June 21. It will give millions of people in southern Africa and Madagascar a 2)rare opportunity to see the total 3)convergence of the moon and the sun. Solar scientists will also be paying attention.

Much of the southern hemisphere will be in the moon's shadow, as the moon passes between the sun and Earth, 4)blocking all solar light except the bright outer 5)atmosphere, or 6)corona 2.

Astronomer 3 Fred Espanak, of the U.S. space agency, NASA, says the darkness will sweep across the southern Atlantic, southern Africa, Madagascar, and the Indian Ocean. "The moon shadow starts rising above the 7)horizon and heading toward you like an 8)impending 9)thunderstorm," he said. "The sky drops from a bright daytime sky to an eerie 4 10)twilight. It's a breathtaking event that makes the hair on the back of your neck stand up."

Thousands of avid 1 eclipse watchers have traveled to southern Africa to 11)witness this dramatic 12)phenomenon. Most are arriving in Zambia's capital, Lusaka, a city that lies entirely 5 within the moon shadow's path.

But the eclipse is more than a spectacle for the 13)multitudes. Because it is an excellent opportunity to solve some of the sun's mysteries, many astronomers 6 are also in Lusaka.

One of them, Jay Pasachoff of Williams College in Massachusetts, says an eclipse offers a unique chance for ground observers to complement 7 the findings of satellites that 14)observe the sun full time.

"That is a unique time when we can study the sun's outer atmosphere from the earth and the only time when we can make certain kinds of scientific observations that enable us to try to understand it," he said. "It is always there, but it is behind the blue sky and we can not study it from the Earth very well because the blue sky is just so bright." The sun's atmosphere is important to life on Earth. NASA's Fred Espanak says it is the site of explosions 15)propelling tons of high-speed 16)atomic particles that bathe Earth - sometimes in such quantity and force that they have a troubling impact.

"Some of these mass ejections can have certain effects on Earth, like causing circuitry on 17)spacecraft to freeze," he said. "It can knock out power 18)grids on the surface of the Earth. It can have long-term effects on climate and meteorology on the Earth. So an understanding of the sun actually helps us understand the Earth environment better."

This eclipse is particularly important because it comes at the end of the 11-year solar cycle when the most intense coronal activity occurs. One of Jay Pasachoff's experiments seeks the reason that the atmosphere reaches a temperature of two million degrees Celsius 8, much hotter than the relatively 9 cool 6,000-degree sun. "So why is the corona hotter than the surface under it? It is as though when you went away from a 19)stove, you get hotter instead of cooler," he said. "Well, there must be some other way of energy getting out of the sun besides just radiation. There must be some wave, in particular, in the 20)magnetic field, and we are studying the waves in the magnetic field to see them."

The Williams College scientist follows eclipses professionally as they appear in various parts of the globe every 18 months or so. But Fred Espanak says they can be 21)addicting even to the non-scientist.

"To see an eclipse is one of the most 22)spectacular natural phenomena 10 anyone could possible experience," he said. "The danger is that once you've seen one total eclipse, you'll want to see another one."