8.30诸多巧合使地球成为宜居星球

1、what makes earth special compared to other planetsby clara moskowitz, staff writer诸多巧合使地球成为宜居星球什么造就了地球较之于其他行星的独特之处？1earth is one special planet.1地球是一颗独特的行星。2it has liquid water, plate tectonics, and an atmosphere that shelters it from the worst of the suns rays. but many scientists agree our planets

2、 most special feature might just be us.2地球上有流动的水、板块构造以及使之免受太阳直射的大气层。但很多科学家认为，地球的最独特之处可能恰恰是地球上的生命。3to enable life, planet earth has a number of ideal features. it is unique among planets in our solar system for having water in its liquid form at the surface, in an amount conducive to life evolving.3地

3、球为生命的存在提供了很多理想条件。它是太阳系中一颗独特的行星，表面有大面积流动的水，有利于生物进化。4the most impressive attribute of the earth is the existence and amount of liquid water on its surface, said geoffrey marcy, an astronomer at the university of california, berkeley who has helped discover dozens of extrasolar planets. no one knows wh

4、y earth has the exact amount of water it does, which is relatively small considering that water molecules outnumber silicate molecules in the galaxy, he said.4伯克利加州大学的天文学家杰弗里.马西说，没有人能确切地知道，地球上到底有多少水，粗略估计，银河系中水分子数要多于硅化物分子数。5the earth is remarkable for its precisely-tuned amount of water, not too much

5、 to cover the mountains, and not so little that its a dry desert, as are mars he said.5他说：“值得一提的是，地球上量恰到好处，水太多则会淹没山脉，像火山一样水太少则会成为干涸的沙漠。”6earths water is also special in that it has remained liquid for so long. how has earth been able to hold on to its oceans while those on other planets freeze or fr

6、y?6同时，地球上的水独特之处还在于它能一直流动。为什么地球能够让海洋水保持流动，而其他行星上的水要么冰冷要么沸腾呢？7many details as to why earth is the only planet with liquid water in our solar system need to be worked out, said diana valencia, a graduate student in earth and planetary sciences at harvard university. certainly the distance to the sun ha

7、s made it possible. a planet much farther in would receive too much energy from the sun, and a planet too far out would quickly freeze.7哈佛大学地球行星学研究生黛安娜.巴伦西亚说：“对于为什么地球是太阳系中唯一拥有流动水的行星，还有很多具体问题有待解决。地球与太阳的距离当然是一个原因。距离太近的行星会吸收过多的太阳能，太远则很快会被冰冻。”8our planets just right location in the solar system has help

8、ed, as has its system of plate tectonics the slip-sliding movements of earths crust that are thought to have created the planets towering mountain ranges and plummeting ocean depths.8地球在太阳系中“恰到好处”的位置使它受益，而板块构造体系-地球外壳的滑移运动也是如此。具信，正是地壳运动形成了地球表面高耸的山峰和深邃的海洋。9the fact that earth has plate tectonics allow

9、s for the carbon-silicate cycle to operate over geological timescales, valencia said. with the carbon-silicate cycle, the levels of carbon in the atmosphere get regulated to keep the surface temperature around that of liquid water.9巴伦西亚说：“地球的板块构造使碳硅化合物在地质年代中不断循环。由于这一循环，大气中碳的含量得到调节，从而保持了流动水域范围的表面温度。”

10、10plate tectonics and water are inextricably linked. not only does plate tectonics enable liquid water to exist by way of regulating the temperature, but many scientists have argued water enables plate tectonics to happen.10板块构造和水密切相关。板块构造不仅能通过调节温度使水流动，同时，很多科学家都认为水促成了板块构造。11without water the planet

11、would be geologically dead, said caltechs mike brown, water is what lubricates plate tectonics, which is what leads to the extreme difference between continents and seafloors, the large amount of earthquakes and volcanoes, fresh mountain-building. venus has no water, no plate tectonics, no deep sea

12、floor, no steep mountains, no continents, probably few earthquakes or volcanoes. a much less geologically interesting place!11加州理工大学的迈克.布朗说：“如果没有水，在地质学上这个行星就是死的。水润滑了板块构造，而板块构造导致了大陆和海底之间的显著区别，引发了地震和火山，改变了山脉的面貌。金星上没有水，没有板块构造，没有深邃的海底，没有屹立的山峰，没有大陆，可能也极少有地震或火山。一个几乎毫无生气的地方！”12another just-right aspect of

13、earth is its size: if it was much smaller, it wouldnt be able to hold on to our precious atmosphere, but much larger and it might be a gas giant too hot for life.12地球的大小也“恰到好处”：太小就无法吸附宝贵的大气层，太大则不可能太热使生命生存。13the presence of jupiter, blocking earth from much of the incoming debris, has also helped ear

14、th become a safe haven for life. jupiter acts like a giant broom, sweeping the solar system of debris that could snuff out life in one fatal blow. this protective effect was particularly helpful in the solar systems early years, when earth still got pummeled but, scientists say, not nearly as bad as

15、 would have been the case without jupiter.13木星的存在为地球当住了大部分天体碎片，也有助于地球成为生命的“安全港”。木星就象一把巨大的扫帚，清扫太阳系中的碎片-一旦被这些大大小小的岩石击中，生命就会戛然而止。在太阳系早期，这一保护作用非常有用，尽管当时地球仍然受到撞击，但科学家说，如果没有木星，情况会糟糕得多。14life on earth may also owe a debt to our nearest celestial neighbor, the moon.14地球上的生命还应感谢距离我们最近的天体月球15earths moon stabi

16、lizes our planets rotation, preventing drastic movements of the poles that could cause massive changes in climate that some scientists think could have doomed any chance for budding life to form or evolve.the moon also helpfully pulls the oceans tides, which scientists suggest might have been the perfect place for early life to begin evolving to survive on land. 15月球使地球稳定稳定旋转，防止地球两极剧烈运动而导致气候剧烈变化。一些科学家认为，要是发生这样的变化，孕育着的生命就不可能形成或进化。一些科学家认为，要是发生这样的变化，孕育着的生命就不可能形成或进化，孕育着的生命就不可能形成或进化。同时，月球也有效地引发潮汐，科学家认为，海洋可能是早期生命开始进化得以在陆地生存的最佳环境。16though e