Venus (金星) is close to the earth. It is the second planet from the sun. The earth is the third planet from the sun. Venus is similar (相似的) to the earth in size and mass (质量). It is often described as the earth’s “sister”.

Scientists have been learning about Venus for a long time. First they looked at Venus through telescopes (望远镜). But Venus is covered with thick clouds. Scientists could not see Venus well through the clouds. So they made guesses about it.

For a long time, scientists thought that Venus had water and plants. They thought Venus might have animals too. But they didn’t know for sure.

Then scientists found a way to learn more about Venus. In the 1960s, they began sending probes (航天探测器) to Venus. The probes flew through the thick clouds. They took pictures of Venus up close. They found out many things too. The probes sent the pictures and things they found out back to the scientists.

The scientists learned a lot from the probes. First they learned that most of their guesses were not right. And they learned that Venus is very hot.

After that, scientists knew they could not send people to Venus. But they still wanted to know more about it. So they sent new probes. These new probes took great pictures of the planet. The pictures showed that Venus has plains (平原) and mountains! And in some ways, Venus looks like the earth.

Scientists think that there has been life on earth for millions of years. However, we haven’t found life on other planets yet. The earth is a planet and it goes around the sun. And there are seven other planets that also go around the sun. The sun and its planets are called the solar system. The solar system is a small part of the universe.

Scientists have launched many spaceships to explore other planets in the solar system. Some spaceships have gone beyond the solar system. However, no one has discovered any life in space yet.

Why has no one from other planets sent us a message? Have they tried to send information to us? With so many stars in space, are we alone, or is there life on other planets in space?

A group of scientists discovered a gas called phosphine(磷化氢) on Venus(金星). That means there may be living things on the planet, which made many people start to imagine the talk between aliens and humans. A reporter from Washington Post wrote a letter to people of Earth on behalf of(代表) the citizens on Venus.

6 . 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 Shostak and Alexandra Barnett are astronomers(天文学家). They believe intelligent life exists (存在) somewhere in the universe. They also think we will soon contact these beings(人：生物).

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

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

Have beings from space already visited Earth? "Probably not," says Shostak. "It's a long way. 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 receive their messages. However, this is changing. By 2025, we could make contact with other life forms in our universe and we might help each other.

7 . Hey! The people of the earth. Can you hear this radio message? Do not be afraid! We come in peace from another planet— and why not? We are your cousins. We are men, as you are. We have been here before.

You will see a huge spaceship, a few hours from now. We are flying towards the solar system (太阳系) almost as fast as this radio message. Your sun is already in sight. Our ancestors (祖先) and yours shared the sun ten million years ago. I’m sure you have forgotten your history while we have remembered ours.

Our ancestors lived on the Earth when dinosaurs were dying. Sadly, they could hardly save the beasts. Your planet was very warm then. Our ancestors believed it would make a nice home for them.

They were wrong. Though we were masters of space, we knew so little about the Earth.

For millions of summers — there were no winters in those ancient days — the Earth had rapid (飞速的) development. It took about thirty years to fly from one planet to another, so our ancestors seldom travelled in space. But they never felt lonely. They kept in touch with their relatives and friends on other planets. Three or four times every century, starships would call and bring them space news.

But two million years ago, the Earth began to change. The temperatures fell quickly. The ground was covered with snow and ice. At that time, however, our ancestors knew little about that. Those who had called the Earth their home believed there was just a strange disease spreading on the earth. The disease wouldn’t cause death to them, but it would bring much pain and do harm to men’s health.

8 . Many people know that rubbish is a big problem on planet Earth. What many people don't know is that junk has become a problem in outer space too.

According to BBC News, there are more than 22, 000 pieces of space junk floating around the earth. And these are just the things that we can see from the surface of the earth by telescopes (望远镜). There are also millions of smaller pieces of junk that we can't see.

Objects, like bits of old space rockets or satellites, move around the planet at very high speeds, so fast that even a very small piece can break important satellites or become dangerous to astronauts. If the tiniest piece of junk crashed into a spaceship, it could damage the vehicle (交通工具).

To make things worse, when two objects in space crash, they break into many smaller pieces. For example, when a U. S. satellite hit an old Russian rocket in 2009, it broke into more than 2,000 pieces, increasing the amount of space junk.

To reduce additional space junk, countries have agreed that all new space tools can only stay in space for 25 years at most. Each tool must be built to fall safely into the earth's atmosphere after that time. In the upper parts of the atmosphere, it will burn up.

 Many scientists are also suggesting different ways to clean up space junk. In England scientists are testing a metal net that can be fired into space junk. The net catches the junk and then pulls it into the earth's atmosphere to burn up. The Germans are building robots that can collect pieces of space junk and bring them back to Earth to be safely destroyed.

 "The problem is becoming more challenging because we're sending more objects into space to help people use their mobile phones and computers," says Marco Castronuovo, an Italian space researcher.

 "The time to act is now. The longer we leave the problem, the bigger it will become," he says.

9 . How would you like to live in space someday? Some people already do--on a space station. The station circles the Earth 2230 miles above us. It moves around our planet at over 17,000 miles per hour.

Astronauts from different countries have called the space station home since the year 2000. Groups of three people take turns living on the station. They travel between their space home and the Earth on the space shuttle(航天飞机). What's it like to live on the space station? “It's like taking a four-month camping trip--in space!" says John Charles, a NASA scientist. The members of the station crew (工作人员) eat dried food, bathe with wet cloths and sleep in sleeping bags. They have to tie the sleeping bags to a wall before they sleep. If they don't do that, they will float(漂浮)around all night.

The weightlessness (失重) of space can be fun. The crew members like to jump up and down.

They also like to play catch in slow motion.

There's work to be done, too. The space station is a busy place. The station's crew members do science experiments. They also spend a lot of their time adding new parts to the station. The space shuttle brings the parts. The astronauts sometimes make space walks outside the station to connect the new parts. Building a house can take less than a year. Building the space station will take at least eight years!

A trip to space

by Jerry

10 October, 2017

I’m so happy! Tomorrow I’ll be one of the first students to travel into space. The spaceship will leave the Earth at 9 a.m. It’ll take us to the Moon. I can’t wait.

The Moon is around 380,000 kilometers from the Earth, so it’ll take us about four days to get there. There’s no gravity in space, so we’ll all be able to float around in the spaceship. We’ll have to tie ourselves to our beds so that we won’t float away in our sleep! Without gravity, our bodies may get weak, so we’ll have to do exercise every day.

When we arrive, I’m going to walk on the Moon. I’ll have to wear a spacesuit to help me breathe because there’s no air on the Moon. I’ m going to take as many photos as I can, that is, if my camera still works up there well.