1 . Some people believe that humans could live on the planet Mars by the year 2100. Our own planet, the Earth, is becoming more and more crowded and polluted. It is hoped that people could start all over again and build a better world on Mars. Here is what life there could be like.

At present, our spacecraft are too slow to carry large numbers of passengers to Mars—it would take months. With the development of technology, by the year 2100, the journey might only take about 20 minutes in spacecraft that travel at the speed of light! However, the spacecraft would travel really fast, so the journey to Mars might be quite uncomfortable. Many people would feel ill.

Humans can’t live without water, air or food. So far, nobody knows whether there would be enough water or air on Mars for people. Moreover, scientists are not sure whether plants could grow on Mars. Food would most probably be in the form of pills (药片) and would not be so tasty.

Compared with life on the earth, life on Mars would be better in some ways. People would have more space. They might live in houses with huge comfortable rooms. Also, robots would do most of their work so that they could have more time to relax. There would probably be no schools on Mars. Every student would study at online schools with “e-teachers”.

Life on Mars would be interesting and challenging (有挑战性的). However, it may take hundreds of years to make it true. So the most important thing we need to do now is to protect our beautiful blue planet—the Earth!

The moon is the earth’s closest neighbor. It is the brightest object in the night sky. Scientists have studied the moon for thousands of years.

The moon is about 4.5 billion years old. It is made of rocks. It is covered with craters (火山口). They were made when objects hit the moon’s surface.

The moon has no weather. That means there is no wind or rain. Footprints (脚印) left by astronauts could last billions of years.

The moon has eight phases (月相). Once a month, we see a full moon. Sometimes we can’t see a full moon at all. The shape we see depends on how the earth, the sun, and the moon line up.

Only 12 people have walked on the moon. U.S. astronaut Neil Armstrong was the first one in 1969. He took a photo of Edwin Aldrin.

The universe is very big. But how large is the universe? It is impossible     1     how large the universe is.

But we know the earth is our home. It is a planet and it     2     around the sun. The moon goes around the earth. There are seven other planets go around the sun. The sun and its planets are a system     3     the solar system. So far, some astronauts     4     to the moon. Some scientists     5     many spaceships to some other planets. But we haven’t     6     life on other planets, because none of them     7     an environment like the earth.

Scientists have also found many other galaxies in the universe. But they are very far away, so no spaceship has travelled far enough     8     them. Is there any life out of the solar system? Have there been visitors to the earth from other planets? I think there is still a long way     9     to know that. When I grow up, I     10     an astronaut and work for China’s space station.

5 . From a plane you can see the fields, cities, mountains or rivers below. If you go into space, you see more and more of the earth. Many man-made satellites (人造卫星) are sent into space to look at the earth, the stars and other planets and learn more about them.

The moon is our neighbor in space. It is smaller than the earth. Plants can’t grow on the moon because there’s no air or water on it.

The moon hasn’t got its own light. It shines back the light of the sun. When the sun is shining on the side of the moon that faces us, it looks like a great round ball. We can’t see the moon when the sun is shining on the side of the moon that faces away from us.

In fact, the moon is far away from us. It is three hundred and eighty thousand kilometres away from the earth. Of course, we can fly to the moon in a spaceship. A spaceship flies very, very fast. It only takes more than three days to get there by spaceship!

8 . Venus, Jupiter, Mercury and Saturn are four planets in the solar system. But do you know how they got their English names? If not, just look ahead.

10 . Would you like to take a trip to the moon? People have already landed on the moon. Some day, the moon might become a popular place to visit. How will a trip to the moon be? Here are some facts.

There is no oxygen (氧气) or water on the moon. In order to stay alive (活着), you would have to take your own oxygen and water. It is silent (寂静地) on the moon. Sounds can’t be carried from place to place because there is no air. On the moon, the temperature goes down to 240℃ below (在……以下) 0℃ at night, and it warms up to 212℃ above 0℃ during the day.

What will the surface (表面) of the moon look like? The moon has more than 30,000 holes on it. One of the biggest is 146 miles wide.

When you walk on the moon, you’ll feel light on your feet. That’s because you weigh only about 20 pounds on the moon. You might forget what day it is there because a moon day lasts for two weeks. But you won’t need an umbrella anymore because it never rains on the moon. And the weather on the moon never changes at all.