8.30诸多巧合使地球成为宜居星球.doc

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？ [1]Earth is one special planet. [1]地球是一颗独特的行星。 [2]It has liquid water, plate tectonics, and an atmosphere that shelters it from the worst of the suns rays. But many scientists agree our planets 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。 [3]To 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。 [4]The 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 why 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。 [5]The Earth is remarkable for its precisely-tuned amount of water, not too much 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。” [6]Earths 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 fry? [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？ [7]Many 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 has 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