The word "light" is used in many expressions. Most of them are used as good meanings. This may be because light help us to see. Without it, we couldn't live.
Cosmologists think the universe started about 14 billion years ago. They believe that all the matter in the universe was in a small ball. This ball got very hot and expanded really quickly again and again. And when it became cooler after millions of years, it became star or planet. When the universe expanded and cooled, matters lost energy and some became light. Light comes from stars. The light of the earth comes from the sun. The sun gives us not only day and night but warmth. Often the moon is thought that it makes own light and shine, but it only reflects light from the sun. Because the moon moves around the earth, the place which the sun shines on is different day by day. That's why the moon's shape looks different.
We can see about 2,500 stars in the night sky. Though there are more stars in space, but we can't see them. Cosmologies can see them by using large telescope.
There are no words which are too different to read in this book. I wrote about the part of this book. But there are more things about not only light from stars but natural light and artificial light. I think it is easy for you to read this book and know many things about light. I recommend it!
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