1 A2 aliens

CHAPTER 1 Little Green Men IS THERE INTELLIGENT LIFE BEYOND EARTH? SCIENTISTS ARE TRYING TO FIND OUT. Do you think there are aliens that live on other planets in the universe? What do you think they look like? In science-fiction books and Hollywood movies, the aliens are often "little green men" with long, thin bodies, very large eyes, and hands with only three long fingers. They travel in "flying saucers." In some movies, like E.T. the Extra-Terrestrial, the alien is very kind and friendly. In other movies, like The War of the Worlds, the aliens are dangerous. They want to kill everyone on Earth.

第一章小绿人地球之外有智慧生命吗？ 科学家们正在努力寻找答案。 你认为宇宙中的其他星球上有外星人吗？ 你觉得他们长什么样? 在科幻小说和好莱坞电影中，外星人通常是“小绿人”，身体又瘦又长，眼睛很大，手只有三个长长的手指。 他们乘坐“飞碟”旅行。 在一些电影中，像E.T.外星人，外星人是非常善良和友好的。 在其他电影中，比如《世界大战》，外星人是危险的。 他们想杀死地球上的所有人。

No one knows what aliens really look like— or if they really do exist. However, some scientists think that the universe is so big that intelligent life must exist beyond our world. But scientists are not waiting for aliens to come to Earth in flying saucers. They think that the first contact with aliens will be with messages. So scientists are trying to find messages from aliens— and at the same time, they are sending messages. They hope that their messages can be the beginning of communication with aliens. The scientific way to say "aliens" is "extraterrestrial intelligence." Extra means "out" and terrestrial means "of Earth." So extraterrestrial intelligence means any intelligent life-form that lives outside of Earth. Do you think aliens will receive our messages? Will they communicate with us in words or in another way, like musical sounds? That's what the aliens did in the movie Close Encounters of the Third Kind.

没有人知道外星人到底长什么样子——或者他们是否真的存在。 然而，一些科学家认为，宇宙是如此之大，智慧生命一定存在于我们的世界之外。 但科学家们并没有坐等外星人乘坐飞碟来到地球。 他们认为与外星人的第一次接触将是传递信息。 因此，科学家们正在努力寻找来自外星人的信息——与此同时，他们也在发送信息。 他们希望他们的信息能成为与外星人交流的开端。 “外星人”的科学说法是“外星智慧生物”。 Extra的意思是“在外面”，terrestrial的意思是“在地球上”。 所以地外智慧指的是任何生活在地球之外的智能生命形式。 你认为外星人会收到我们的信息吗？ 它们会用语言还是用其他方式，比如音乐声音，与我们交流？ 电影《第三类接触》中的外星人就是这么做的。

CHAPTER 2 SETI COMMUNICATING WITH EXTRATERRESTRIAL LIFE-FORMS IS NOT JUST SCIENCE FICTION. IT IS REAL SCIENCE. In the 1997 movie Contact, a scientist is trying to find proof that extraterrestrial life exists. She uses a special radio to listen for messages. One day, she hears messages from a far away star. The messages tell her how to build a machine that will let her travel to that star. Does this sound like a strange story? Well, it's based on the work of real people at a real organization that wants to make contact with extraterrestrial life-forms.

seti与外星生命的交流不仅仅是科幻小说。 这是真正的科学。在1997年的电影《超时空接触》中，一位科学家试图寻找外星生命存在的证据。 她用一种特殊的收音机收听信息。 一天，她听到了来自遥远星球的信息。 这些信息告诉她如何建造一台机器，让她去那个星球旅行。 这听起来是不是很奇怪？ 嗯，它是基于一个真实组织的真实人的工作，这个组织想要与外星生命接触。

It's called the SETI Institute. SETI stands for "Search for Extraterrestrial Intelligence." SETI has many important scientists. They are trying to find out if there is life in the universe beyond Earth. The SETI Institute was started in 1984 in California, USA. But the search for extraterrestrial intelligence started earlier. In 1960, a young radio astronomer named Frank Drake started the first search for signals from other solar systems. He used a 26-meter antenna, but he didn't hear anything. Many other scientists, however, were interested in his research. In 1974 the famous Arecibo Message was sent from a 305-meter antenna. It was the strongest message ever sent. The message was a simple picture. Scientists think prime numbers may be easier for aliens to understand, so the picture is 73 lines of 23 characters per line (73 and 23 are prime numbers). The picture shows a person, our solar system, DNA, and some of the chemicals of life.

它被称为SETI研究所。 SETI的意思是“寻找外星智慧”。 SETI有很多重要的科学家。 他们正试图查明地球以外的宇宙中是否有生命。 SETI研究所于1984年在美国加利福尼亚州成立。 但对地外文明的探索开始得更早。 1960年，一位名叫弗兰克·德雷克的年轻射电天文学家开始了对其他太阳系信号的首次搜索。 他用了一个26米长的天线，但他什么也没听到。 然而，许多其他科学家对他的研究很感兴趣。 1974年，著名的阿雷西博信息从305米的天线发出。 这是有史以来最强烈的信息。 信息是一张简单的图片。 科学家认为质数可能更容易让外星人理解，所以这幅图是73行，每行23个字符（73和23是质数）。 这张照片展示了一个人、我们的太阳系、DNA和一些生命的化学物质。

Ten years later, a group of scientists started the SETI Institute. Today, SETI does many different kinds of research. One part of SETI uses radio to listen for messages from other intelligent life-forms. Why radio? People started sending radio signals into space about 100 years ago. We do it every time we turn on a radio, a TV, or use radar. So, maybe, other intelligent life-forms send out radio signals, too. Maybe one day we will hear alien radio programs! The SETI Institute also uses telescopes to look for extraterrestrial intelligence. What do they look for? Short but strong lights that are not natural. They think these lights could show that aliens are trying to send signals to us.

十年后，一群科学家成立了SETI研究所。 今天，SETI做了许多不同种类的研究。 SETI的一部分使用无线电来收听来自其他智能生命形式的信息。 为什么收音机吗?大约100年前，人们开始向太空发送无线电信号。 我们每次打开收音机、电视或使用雷达时都会这样做。 所以，也许其他智能生命形式也会发出无线电信号。 也许有一天我们会听到外星人的广播节目！SETI研究所也使用望远镜寻找外星智慧。 他们在寻找什么？不自然的短而强的光。 他们认为这些光可能表明外星人正试图向我们发送信号。

Another part of SETI, the Carl Sagan Center, studies astrobiology, which is the study of life in the universe. They want to answer these questions: Where did we come from? Are we alone? The Carl Sagan Center also researches habitability— if and how people can live in a place. They study different kinds of habitability on Earth, in very difficult places like the Arctic, Antarctica, the highest mountains, and the bottom of the ocean. They also research habitability in other places in our solar system. They want to find out if there are other planets where people could live. To do this, scientists from the National Aeronautics and Space Administration (NASA) fly into space, and they also use the world's best telescopes to look into space.

SETI的另一个部分，卡尔萨根中心，研究天体生物学，也就是研究宇宙中的生命。 他们想要回答这些问题：我们从哪里来？ 我们是孤独的吗？卡尔·萨根中心还研究可居住性，即人们是否可以以及如何居住在一个地方。 他们研究地球上不同的宜居性，在北极、南极洲、最高的山脉和海底等非常困难的地方。 他们还研究了太阳系其他地方的宜居性。 他们想知道是否有其他星球可供人类居住。 为了做到这一点，美国国家航空航天局（NASA）的科学家们飞向太空，他们还使用世界上最好的望远镜观察太空。