探索频道英语听力 Cosmos 宇宙的边疆14
2009-10-17来源:和谐英语
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250 years later, the earth was all explored. New adventurers now look to the planets and the stars. The galaxies were recognized as great aggregates of stars, island universes, millions of light years away.
In the 1920s, astronomers had begun to measure the speeds of distant galaxies.
(what time is it? 7:15, Well, lights off. please).
They found that the galaxies were flying away form one another. To the astonishment of everyone, the entire universe was expanding. We had begun to plumb the true depths of time and space. The long collective enterprise of science has revealed a universe some 15 billions years old, the time since the explosive birth of the cosmos---the Big Bang.
The cosmos calendar compresses the local history of the universe into a single year. If the universe began on January 1st, it was not until May that the Milky Way formed. Other planetary systems may have appeared in June, July and August, but our sun and earth, not until mid-September, life arose, soon after. Everything humans have ever done occurred in that bright speck at the lower right of the cosmic calendar. The Big Bang is at upper left in the first second of January 1st, 15 billions years later, is our present time, the last……