You know that everything which affects your senses is called "matter, " and that the earth is a great ball of matter. 你知道, 任何能够对你的感官造成影响的东西都叫做“物质”, 而地球则是一个由各种物质组成的大球。

　　Is there any matter outside this earth? 那么, 地球之外是否存在物质呢?

　　You need only look up into the sky to get an answer to this question. 抬头望天, 你就能找到答案。

　　In the daytime you can see a great hot ball of matter called the sun, and at night you can sometimes see another large shining ball called the moon. 白天, 你能够看到一个炽热的物质大球, 这就是太阳；到了晚上, 有时候能看到天空中悬挂的另一个闪亮的球体——月亮。

　　On a clear night you can also see in the sky a great many bright pieces of matter which are called stars. 如果遇到一个晴朗的夜晚, 那么你还能够在天空中看到许多名叫星星的发光物质。

　　Did you ever try to count the stars? 你有没有试过去数一下星星的数量?

　　On a clear, fine night, when the moon is not shining, you can see with your naked eyes about three thousand stars. 在晴朗的夜晚, 当月亮不再闪烁的时候, 我们凭借肉眼就能够看到大约三千颗星星。

　　But you can see only one half of the sky at one time, and there are about as many stars in the other half of the sky. 然而, 我们无法看到天空的全貌, 因为地球的另一侧还有一片天空, 而那里也悬挂着同样多数量的星星。

　　So we may say that in the whole of the sky there are about six thousand stars which can be seen by the naked eye. 那么, 我们可以这样说, 仅凭肉眼观察, 整个天空中应该有大约六千颗星星。

　　If we use a telescope, we shall see a great many more. 如果使用望远镜的话, 我们就能够看到更多星星。

　　Some stars move very slowly about the sky, changing their places among the other stars little by little every night. 有些星星能够在天空中慢慢移动, 每天晚上, 它们都会缓慢穿梭在其他星星之间, 改变自己的位置。

　　These stars, five of which we can see with the naked eye, are called planets, and they are much nearer to us than the other stars. 我们通过肉眼就能够观察到五颗这样的星星, 它们就是行星。相对其他星星来说, 它们距离地球更近。

　　The earth on which we live is also a planet. 我们所居住的地球同样也是行星。

　　Our earth and the other planets move round the sun. 地球与其他行星一样, 围绕太阳运动。

　　All the other stars are called fixed stars, because they do not move round the sun. 其他星星则都被称作恒星, 因为它们没有围绕太阳进行运动。

　　The fixed stars form sets or groups, to which names have been given. 这些恒星可以构成星群或星团, 而它们也都有自己的名称。

　　I daresay that you know the group of seven stars called by some the "Great Bear, " 我敢肯定, 你绝对知道由七颗星星组成的“大熊座”星群,

　　but known to many children as "The Wagon and Horses.  不多对于很多孩子来说, 他们更熟悉的名字还是“马车与大马”。