徐燕飛

There are nine planets1 in our solar system2. All of them move around the Sun. The planet closest to the Sun is named Mercury3. The Greeks said Mercury was the messenger of the gods. The second planet from the Sun is named Venus4. Venus was the Greek goddess of beauty. Earth is the third planet from the Sun. It is about the same size as Venus. After Earth is Mars5， which is named after the Greek god of war. The other five planets are Jupiter6， Saturn7， Uranus8， Neptune9 and Pluto10. They， too， are named after Greek gods.

Jupiter

Jupiter， the fifth planet from the Sun. It takes this planet from the Sun. It takes this planet almost 12 years to orbit11 the Sun. Jupiter's ring is very difficult to see from Earth. Jupiter is the largest planet in our solar system. It is 11 times bigger than Earth！

Scientist have been able to learn much about this planet because of the information received from Voyager 1 in 1979. They know that we cannot send a spacecraft to the surface of Jupiter as we have done with the Moon. The surface of Jupiter is gas12.

Pluto

Pluto is the ninth planet in our solar system. It is 3，700 million miles from the Sun. It cannot be seen from Earth without a telescope13. Maybe that is why it was named Pluto. Pluto was the Greek god of the underworld. For years， scientist thought there was a ninth planet. But it was not until 1930 that a young scientist proved14 Pluto existed15. His name was Clyde Tombaugh. He compared pictures of the sky near Pluto taken at different times. He noticed one big “star” was in a different place in different pictures. It was not a star. It was a planet moving around the Sun.

Notes： 1. planet n. 行星 2. solar system 太陽系 3. Mercury 水星 4. Venus 金星 5. Mars 火星 6. Jupiter 木星 7. Saturn 土星 8. Uranus 天王星 9. Neptune 海王星 10. Pluto 冥王星 11. orbit vt. 繞軌道而行 12. gas n. 氣體

13. telescope n. 望遠(yuǎn)鏡 14. prove v. 證明 15. exist vt. 存在

I. Answer the questions about our solar system.

1. How many planets are there in our solar system？

2. What do the planets circle？

3. What are the planets named after？

4. Which planet is closed to the Sun？

5. Which planet is about the same size as the Earth？

II. Answer these questions about Jupiter.

1. In what year did Voyager 1 sent us more information about Jupiter？

2. Why can't we send a spacecraft to land on Jupiter？

3. What is the largest planet in our solar system？

4. Jupiter is the ______ planet from the Sun.

5. How many times is Jupiter bigger than the Earth？

III. Answer these questions about Pluto.

1. Who discovered Pluto？

2. When did he prove Pluto exist？

3. Why was the new planet named Pluto？

4. How was Pluto discovered？

5. What is Pluto's distance from the Sun？