共用题干 Early Ideas about the Universe

1 Early man got his ideas about the universe by looking at the stars as you do.He
observed carefully,and learned many things about the sun,the moon,and the stars.
2 Suppose you were asked to collect evidence about the sun as early man did.You might
go out morning after morning and see it come up in the east.Even on cloudy mornings,you
would observe that the darkness goes away and the world becomes light.You might not see
the sun but would be sure it is there,because you notice that the earth warms up.As you
continued,the sun climbs higher in the sky each day during part of the year. It stays in the
sky longer. The earth gets warmer. Things begin to grow. It is spring and then summer.
3 After a while the sun stays in the sky for shorter and shorter periods.Many plants begin
to die.Leaves fall.Winter comes.Year after year this is repeated and you cannot tell
exactly why it happens.But you realize that the sun seems to make the difference.
Primitive（原始的）man felt that since the sun was so powerful it must be a god. It may
seem silly to us now to worship（崇拜）a sun-god, but primitive man was right about the
importance of the sun to life on earth.
4 You have been told that the world is round.But suppose no one had ever taught you
that the world was like a huge ball.Would you have ever thought of it yourself?You cannot
see the curve（曲线）of the earth at once. You would have no idea of how big it was.
That"s why early man believed that the earth was small and flat.Such ideas appeared from
the evidence they had.
5 If you watch the stars night after night,you will see them rise and set.As you look at
the sky,it is not difficult to imagine that you are in the center of a vast collection of twinkling
（闪烁）lights. Some early astronomers（天文学家）believed the sky was a crystal shell or
series of crystal shells,one inside the other. They believed this because that is what the
night sky looked like.For many centuries,men believed that the earth was the center of
the universe and that the sun,the moon,and the stars circled around it. Paragraph 5_________