原文

Recent developments in astronomy have made it possible to detect planets in our won Milky Way and in other galaxies. This is a major achievement because, in relative terms, planets are very small and old not emit light. Finding planets is proving hard enough, but finding life on them will prove infinitely more difficult. The first question to answer is whether a planet can actually support life. In our won solar system, for example, Venus is far too hot and Mars is far too cold to support life. Only the Earth provides ideal conditions, and even here it has taken more than four billion years for plant and animal life to evolve.

Whether a planet can support life depends on the size and brightness of its star, that is its 'sun'. Imagine a star up t twenty times larger, brighter, brighter and hotter than our own sun. A planet would have to be a very long way from it to be capable of supporting life. Alternatively, if the star were small, the life-supporting planet would have to have a close orbit round it and also provide the perfect conditions for life forms to develop. But how would we find such a planet? At present, there is no telescope in existence that is capable of detecting the presence of life. The development of such a telescope will be one of the great astronomical projects of the twenty-first century.

It is impossible to look for life on another planet using earth-based telescopes. Our own warm atmosphere and the heat generated by the telescope would make it impossible to detect objects as small as planets. Even a telescope in orbit round the earth, like the very successful Hubble telescope, would not be suitable because of the dust particles iron solar system. A telescope would have to be as far away as the planet Jupiter to look for life in outer space, because the dust becomes thinner the further we travel towards the outer edges of our own solar system. Once we detected a planet, we would have to find a way of blotting out the light from its star, so that we would be able to 'see' the planet properly and analyze its atmosphere. In the first instance, we would be looking for plant life, rather than 'little green men'. The life forms most likely to develop on a planet would be bacteria. It is bacteria that have generated the oxygen we breathe on earth. For most of the earth's history they have been the only form of life on our planet. As Earth-dwellers, we always cherish the hope that we will be visited by little green men and that we will be able to communicate with them. But this hope is always in the realms of science fiction. If we were able to discover lowly forms of life like bacteria on another planet, it would completely change our view of ourselves. As Daniel Goldin of NASA observed, 'Finding life elsewhere would change everything. No human endeavor or thought would be unchanged by it."

译文

以下是用户提供的英文文章的中文翻译。我会尽量遵循《新概念英语》官方译文的风格，即语言简洁、优雅、准确，句式清晰流畅，富有节奏感，并符合中文母语者的阅读习惯。对于专业术语（如“Milky Way”翻译为“银河系”），我保留其原意，并使用自然的中文表达，同时避免直译。原文中未包含特殊字符串如制表符或换行符，因此翻译中未作额外保留。

---

最近的天文学发展使我们能够探测到我们自己的银河系以及其他星系中的行星。这是一项重大的成就，因为从相对的角度来看，行星非常渺小，而且并不发光。找到行星已经够困难的了，但要在它们上面发现生命，将会难上加难。首先需要回答的问题是，一颗行星是否真能支持生命。例如，在我们自己的太阳系中，金星过于炎热，而火星又过于寒冷，都无法支持生命。只有地球提供了理想的条件，而且即使在这里，植物和动物生命的进化也花费了超过四十亿年的时间。

一颗行星是否能支持生命，取决于其恒星的大小和亮度，也就是它的“太阳”。想象一颗比我们自己的太阳大、亮且热二十倍的恒星。一颗行星要想能支持生命，就必须离它非常遥远。反之，如果恒星较小，那么能支持生命的行星就必须绕着它运行在近轨道上，并提供完美的条件让生命形式发展。但我们又该如何找到这样的行星呢？目前，还没有现存的望远镜能够探测到生命的迹象。开发这样的望远镜，将成为二十一世纪伟大的天文项目之一。

使用地球上的望远镜来寻找其他行星上的生命是不可能的。我们温暖的大气层以及望远镜本身产生的热量，会使探测像行星这样微小的物体变得不可能。即使是像大获成功的哈勃望远镜那样绕地球运行的望远镜，也因为太阳系中的尘埃粒子而不适合。一台望远镜必须远至木星的位置，才能在外太空搜寻生命，因为尘埃在向我们太阳系外缘延伸时会变得越来越稀薄。一旦我们探测到一颗行星，我们就必须想办法遮挡其恒星的光线，这样才能正确地“看到”这颗行星，并分析它的 atmosfera。在最初阶段，我们会优先寻找植物生命，而不是“小绿人”。最有可能在行星上发展的生命形式是细菌。正是细菌产生了我们地球上呼吸的氧气。在地球历史的大部分时间里，它们一直是唯一的生命形式。作为地球居民，我们总是怀着希望，有朝一日会被小绿人造访，并能与他们交流。但这种希望始终停留在科幻小说的领域。如果我们能够在另一颗行星上发现像细菌这样的低等生命形式，它将彻底改变我们对自己的看法。正如美国国家航空航天局（NASA）的丹尼尔·戈尔丁所指出的：“在别处发现生命将改变一切。没有人类努力或思想会因此而不变。”

---

此翻译力求准确传达原文意图，同时保持《新概念英语》式的简洁与优雅。例如，句子结构采用自然的中文节奏，避免冗长累赘。对于术语如“Milky Way”（银河系）、“solar system”（太阳系）和“bacteria”（细菌），我使用了标准且流畅的中文表达，以确保清晰易懂。如果原文中涉及的概念（如外星生命可能性）未在《新概念英语》中直接对应，我已根据其风格进行适配，语言亲切却不失严谨。