1.You know that everything which affects your senses is called “matter，”and that the earth is a great ball of matter.Is there any matter outside this earth？You need only look up into the sky to get an answer to this question.
2.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.On a clear night you can also see in the sky a great many bright pieces of matter which are called stars.
3.Did you ever try to count the stars？On a clear，fine night，when the moon is not shining，you can see with your naked eyes about three thousand stars.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.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.
If we use a telescope①，we shall see a great many more.
4.Some stars move very slowly about the sky，changing their places among the other stars little by little every night.These stars，five of which we can see with the naked eye，are called①Telescope，an instrument for seeing things at a distance.
planets，and they are much nearer to us than the other stars.The earth on which we live is also a planet.Our earth and the other planets move round the sun.
GREAT BEAR（大熊座）
5.All the other stars are called fixed stars，because they do not move round the sun.The fixed stars form sets or groups，to which names have been given.I daresay that you know the group of seven stars called by some the “Great Bear，”but known to many children as “The Wagon and Horses.”
6.Each of the fixed stars is a sun，very much like our own sun，but so faraway from the earth that it only looks like a speck of light.
7.The sun is a great ball of hot matter，very much hotter than the hottest fire which we can make.If it were not for the heat which comes from the sun，everything upon the earth would quickly die of cold.
8.If you look at the sun with your naked①eyes，it may hurtthem；but if you smoke a piece of glass over a candle-flame，you can then look at the sun through the darkened glass without any fear of your eyes being hurt by the strong light.
9.The moon is a large ball of matter，but it is not nearly so large as the earth.Have you noticed any markings on the surface of the moon？The dark parts are great plains，and the bright parts are mountains.
10.The moon looks very bright，but the light which it sends to us is only reflected②sunlight.The moon itself is a cold，dark mass of matter；but it looks bright because the sun is shining on it.
①Naked，without protection or covering.
②Reflected，thrown back as in a mirror.
PART OF MOON’S SURFACE（月面的一部分）
11.Here is a fact which will give you some idea①of the distance to the moon：-If there were a railway from the earth to the moon，and if a train were to travel along it day and night at the rate of 60miles an hour，it would take 166days to complete②the journey.
12.The sun is very much bigger than our earth，and therefore bigger still than the moon.But the sun does not look any larger than the moon，because it is so much farther away.The train that would carry us to the moon in 166days would take 177years to reach the sun.
SUMMARY