托福听力必背的 经典段子8

托福听力必背的 经典段子8

　　托福听力段子8.理科段子：天文学

　　In ancient times, many people believed the

　　earth was a flat disc. Well over 2,000 years ago; the ancient Greek

　　philosophers were able to put forward two good arguments proving

　　that it was not. Direct observations of heavenly bodies were the

　　basis of both these arguments. First, the Greeks knew that during

　　eclipses of the moon the earth was between the sun and the moon,

　　and they saw that during these eclipses, the

　　earth’s shadow on the

　　moon was always round, they realized that this could be true only

　　if the earth was spherical, It the earth was a flat disc, then its

　　shadow during eclipses would not be a prefect circle; it would be

　　stretched out into a long ellipse. The second argument was based on

　　what the Greeks saw during their travels. They noticed that the

　　North Star, or Polaris, appeared lower in the sky when they

　　traveled south, in the more northerly regions, the North Star

　　appeared to them to be much higher in the sky. By the way, it was

　　also from this difference in the apparent position of the North

　　Star that the Greeks first calculated the approximate distance

　　around the circumference of the earth, a figure recorded in ancient

　　documents says 400.000 stadium, that’s the plural of the world stadium. Today,

　　it’s not known exactly

　　what length one stadium represents, but let’s say it was about 200 meters, the length

　　of many athletic stadiums. This would make the

　　Greek’s estimate about

　　twice the figure accepted today, a very good estimate for those

　　writing so long before even the first telescope was invented.