课件13张PPT。Unit 4 Astronomy：the science of the stars 学 习 目 标 展 示背 景 知 识 链 接Astronomy is the oldest science known to man.Thousands of years ago man looked at the stars and wondered about the heavens.But man was limited by the six planets that he could see with his eyes alone.The Greeks studied astronomy over 2,000 years ago.They could see the size，colour，and brightness of a star.They could see its place in the sky.They watched the stars move as the seasons changed.But the Greeks had no tools to help themselves study the heavens.Each new tool added to the field of astronomy helped man reach out into space.Until there were telescopes①，man knew a little about the moon.He did not know that the planet called Saturn② had rings around it.His sight was so limited that he could not see all the planets. In the early 1700s，people thought there were only six planets.Before the spectroscope③，man did not know what kind of gases is around the sun or other stars.Without the radiotelescope④，we did not know that radio noises come from far in space.Today，astronomy is a growing science.We have learned more in the last fifty years than in the whole history of astronomy.人类的视野非常有限，看不到所有的行星。在18世纪早期，人们认为只有六颗行星。在分光镜出现之前，人类不知道太阳或其他星球周围有什么样的气体。没有射电望远镜，我们不知道射频噪音来自遥远的太空。如今，天文学是一门日益发展的科学。我们在过去的50年里所了解的要比在整个天文学史上所了解的还要多。Notes ①telescope n．望远镜 ②Saturn n．土星 ③spectroscope n．分光镜 ④radiotelescope n．射电望远镜 Task According to the passage，what helped human beings observe the moon? The appearance of the telescopes
