Is there intelligent (有智力的) life on other planets? For years, scientists said “no.” or “we don’t know.” But today this is changing. Seth Shostakovitch and Alexandra Barnett are astronomers (天文学家). They believe intelligent life exists (存在) 【小题1】 in the universe. They also think we sill soon contact these beings(人；生物).

Why do Shostakovitch and Barnett think intelligent life exists on other planets? The first 【小题2】 is time. Scientists believe the universe is about 12 billion years old. “This is 【小题3】 enough for other planets to have intelligent life,” says Shostakovitch and Barnett. The second reason is size—the universe is huge. “Tools like the Hubble Telescope (哈勃望远镜) have 【小题4】 that there are at least 100 billion galaxies,” says Shostakovitch. “And our galaxy, the Milky Way, has at least 100 billion stars. Some planets going around these stars might be 【小题5】 to Earth.”

In the past, it was hard to look for 【小题6】 of intelligent life in the universe. But now, powerful telescopes (高倍望远镜) allow scientists to 【小题7】 smaller planets—the size of Mars or Earth—in 【小题8】 solar systems. These planets might have intelligent life.

Have beings from space already visited Earth? “Probably not,” says Shostakovitch. “It’s a long way away. However, intelligent beings may contact us in other way, such as radio signals (信号). In fact, they may be trying to communicate with us now, but we don’t have the right tools to 【小题9】 their messages. However, this is changing. By 2025, we could make contact with other life 【小题10】 in our universe and we might help each other.”

From a plane you can see the fields, 【小题1】, mountains or rivers below. If we go into space, we see more and more of the earth. People and man-made satellites are 【小题2】 out into space to look at the earth, the stars and other 【小题3】 and learn more about them.

The moon is our 【小题4】 neighbour in space. It is our satellite and men have visited it already. It is smaller than the earth. 【小题5】 can’t grow on the moon because there’s no air or water on it.

The moon hasn’t its own light. It 【小题6】 back the light of the sun. When the sun is shining on the side of the moon that faces us, it 【小题7】 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 【小题8】.

In fact the moon isn’t as near as it looks. It is three 【小题9】 and eighty thousand kilometres away from the earth. Of course we can fly to the moon in a spaceship. A spaceship 【小题10】 very, very fast, and it flies at about eleven kilometres a second. So it only takes more than three days to get there by spaceship.

Lots of scientists believe that there’s life on other planets. Because of this, they keep doing research about the universe. They have sent astronauts to the moon. And they have 【小题1】 the answer. There’s no life on the moon. Not long ago they 【小题2】 spaceships to Mars. There, they didn’t find life, either. And they found the environment of Mars was 【小题3】 from that of the earth. Then they knew it was 【小题4】 for people to live on Mars.

【小题5】 they haven’t received a message from other planets, they believe that their idea is right. Recently they have 【小题6】 a planet. It’s 【小题7】 Proxima Centauri. It’s very 【小题8】 to our earth. It is just over four light years away. Proxima Centauri is 【小题9】 than the earth. And there’s water on this planet. It 【小题10】 mean that life is possible there. Now scientists are studying this planet. Soon they will tell people the answer.