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 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 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.”

3 . The plan: turn Mars into a blue world with streams and green fields,and then fill it with creatures from the Earth. This idea may sound like something from a science fiction, but it is actually being taken seriously by many researchers. This suggests the future for the “red planet” will be the main topic for discussion at an international conference hosted by NASA this Week. Leading researchers as well as science fiction writers will attend the event. It comes as NASA is preparing a multi-billion-dollar Mars research programme.

“Turning Mars into a little earth has long been a topic in science fiction,” said Dr Michael Mever NASAs senior scientist. “Now with scientists exploring the reality we can ask what the real possibilities of changing Mars.” Most scientists agree that Mars could be turned into a little earth, although much time and money would be needed to achieve this goal. But many experts are shocked by the idea. “We are destroying our own world at an unbelievable speed and now we are talking about ruining another planet,” said Paul Murdin from the Institute of Astronomy, Cambridge, UK.

Over the past months, scientists have become increasingly confident they will find Martian life forms. Europe and Americas robot explorers have found the proof that water, mixed with soil, exists in large amounts on the planet.

In addition, two different groups of scientists announced on March 28 that they had found signs of methane (甲烷) in the Martian atmosphere: the gas is a waste product of living creatures and could be produced by microbes (微生物) living in the red planets soil. But scientists such as Dr. Lisa Pratt, a biologist at Indiana University, say that these microbes will be put in danger by the little earth project.

“Before we have even discovered if there is life on Mars, we are talking about carrying out projects that would destroy all these native life forms, all the strange microbes that we hope to find buried in the soil,” said Dr.Pratt.

Monica Grady, a planetary scientist at the Natural History Museum, London, shares this view.“We cannot risk starting a global experiment that would wipe out the precious information we are looking for,” she said. “This is just wrong.”

4 . A newly discovered planet looks just right for life as we know it, according to an international group of astronomers. Orbiting a star about 500 light-years away, the planet called Kepler-186f is about the same size as Earth. It orbits its star at the right distance for liquid water on the surface. That is a necessary condition for life as we know it.

But it is not exactly like Earth, NASA planetary scientist Elisa Quintana said. "It's more of an Earth's cousin. It's not an Earth's twin. It shares the same characteristics as Earth, but their parent stars are very different," said Quintana.

Kepler-186f orbits a star that is smaller and cooler than our sun. But, writing in the journal Science, the astronomers say the planet appears to be a closer relative than   most of the hundreds of others discovered so far. Some are massive gas-covered giants with thick, crushing atmospheres. Others orbit too close to their stars and are too hot for life.

Two planets discovered last year are in the right orbit and might be good candidates for life, Quintana says, but they are a bit bigger than Earth. "For the first time, we can actually say we now have a planet that is both Earth-sized and orbits in its star's habitable zone," she said.

It may be the first time, but it probably is not the last, says Massachusetts Institute of Technology astrophysicist Sara Seager. "We've been waiting decades to understand how common habitable planets might be, and it's looking like they're really common. And this gives us excitement and motivation to take the next step," said Seager.

The next step would be to look for signs of life in the atmospheres of these distant   worlds. That would take a more sophisticated (高端的；复杂的) space telescope. But budget cuts threaten that mission, says University of California at Los Angeles astrophysicist Ben Zuckerman, "In principle, we could do this in the next few decades. But in practice, because there's no money, it's not gonna happen. It's not gonna happen in my lifetime, for example."

Leaving earthbound concerns behind, NASA's Elisa Quintana believes that when the next-generation space telescope is launched, it will find that we are not alone in the universe.

5 . It was a discovery that could change science. “We hit the jackpot (头奖) here,” said a British scientist, Guillem, about the discovery of a planet “more or less” like Earth that is orbiting Proxima Centauri, the star nearest to our solar system.

What do we know about this exciting new Earth? Well, Proxima b, or “Earth II” as you could call it, is a little bigger than our Earth. Also, since it is so much closer to its red dwarf star than we are to the sun, the sky on its world is orange without any blue at all, creating a forever sunset effect.

There are a lot of questions for life forms that could live on this new planet. As the Chicago Tribune wrote in an article: “First, as reporter Lois Lane asked Superman in the first movie, Do you eat? Do you have poetry? Do you have any interest in visiting other worlds? If so, put Earth on your Must See list.”

The discovery of the planet made the Chicago Tribune newspaper wonder if anyone had seen or heard of the U.S.’ space postcards from its Pioneer 10 and Pioneer 11 space probes, sent up into space in 1972 and the next year.

Included with the probes were pictures of a man and a woman, along with diagrams of the solar system. Gold records were also sent up into space on Voyager probes in 1977. If aliens on Proxima b had played the record, they would have found sounds and images that showed the incredible diversity of Earth.

Aliens might also have heard the message from former U.S. President Jimmy Carter: “This is a present from a small distant world… our sounds, our science, our images, our music, our thoughts and our feelings. We are trying to survive our time so we may live into yours. We hope someday, having solved the problems we face, to join a community of galactic (星系的) civilizations. This record represents our hope and our determination, and our good will in an … awesome universe.”

It might not be time to plan a visit to Proxima b just yet—even if it has an atmosphere—because first, we would need to invent a way to get there in less than the 78,000 years it would take at 36,000 mph (about 57,900 km/h).

“Proxima b looks to us like a promising Plan B, just in case things go really south on this blue planet,” the Chicago Tribune wrote.

In the ancient times, there used to be so many myths about the moon, and all of     1     (they) made the moon more attractive. On the moon, according to the Chinese myth, lived a goddess named Chang'e, who led a lonely life. In the west, up to now, scientists     2     (study) the moon for many years. I wonder if you have received an     3     (invite) to spend a Human Moon Day, which is officially celebrated on July 20 every year. Human Moon Day marks the first human landing on the moon     4     (success) that occurred on July 20,1969. That explains it! Ever since 1969, Human Moon Day has been celebrated in the US to mark one of the     5     (great) achievements in human history.

Human Moon Day is largely celebrated by NASA and space fans. One way to celebrate Human Moon Day is to make something about the moon like cutting paper     6     (moon). Children are made to bake cookies and cut them in the shape of the moon. They also consider     7     (learn) some facts about the moon on this occasion. Exploring the moon on Google Moon is a great idea of getting familiar with our natural satellite. It is especially important that we celebrate Human Moon Day with children.     8     this way, children can learn about     9     happened on July 20, 1969, and understand the importance of this event in the future. It can be said with certainty that humans will devote all their lives to the research into the moon. As for young people, they must go to all lengths to study hard for the future even if there is a long way to go!

Should there be     10     chance for you to go to the moon, who would you like to go with you?

Are we alone in the universe? Scientists have spent years     1     (search) deep into space for signs of life beyond our planet. Now they've discovered what might be life on Venus.

Venus is the second planet from the sun in our solar system. It's one of     2     brightest objects in the night sky. Several billion years ago, the surfaces of Venus and Earth may have been     3     (similar) than now. But today, the surface of Venus is too hot for life. And until recently, Venus's thick clouds were thought to be too poisonous for a living thing     4     (survive) there.

    5     September 14, in the journal Nature Astronomy, scientists reported the discovery of a chemical     6     (call) phosphine(磷化氢)in the clouds of Venus. On Earth, the phosphine gas     7     (give) off by living things. Scientists aren't yet able to prove that life on Venus is     8     is producing the phosphine. But they can't explain the source of the gas in any other way.

The discovery of life beyond Earth would teach us more about the universe     9     our place in it. To Sousa-Silva, an astrochemist of Harvard University, it would say something about our     10     (important). “I like finding out that we as humans aren't that special,” she says.