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.”

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

But we know the earth is our home. It is a planet and it 【小题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 【小题3】 the solar system. So far, some astronauts 【小题4】 to the moon. Some scientists 【小题5】 many spaceships to some other planets. But we haven’t 【小题6】 life on other planets, because none of them 【小题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 【小题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 【小题9】 to know that. When I grow up, I 【小题10】 an astronaut and work for China’s space station.

Lots of scientists believe there’s life on other planets. Because of this, they keep doing research 【小题1】 the universe. They have sent astronauts to the moon. And they have 【小题2】 the answer. There’s no life on the moon. Not long ago they 【小题3】 spaceships to Mars. There, they didn’t find life. And they found the environment of Mars was 【小题4】 from that of the earth. Then they knew it was 【小题5】 for people to live on Mars.

【小题6】 they haven’t received a message from other planets, they believe their idea is right. Recently they have discovered a planet. It’s 【小题7】 Proxima Centauri (比邻星). 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. That 【小题10】 mean that life is possible there. Now scientists are studying this planet. Soon they will tell people the answer.