托福听力必背的 经典段子8

通过admin

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.

关于作者

admin administrator