万物简史 第349期:孤独的行星(14)

 　　The figures have since been refined and made a little more generous, 自那以后，这两个数字被更精确地测算了一遍，放宽了一点，

　　5 percent nearer and 15 percent farther are thought to be more accurate assessments¹ for our zone of habitability—but that is still a narrow belt. 再近5%，再远15%，但仍是个窄带。

　　(The discovery of extremophiles in the boiling mudpots of Yellowstone and similar organisms found elsewhere （由于在黄石公园沸腾的泥潭里发现了极端微生物和在别处发现了类似的微生物，

　　made scientists realize that actually life of a type could range much farther than that-even, perhaps, beneath the icy skin of Pluto². 科学家们认识到，某种真正的生命的分布范围要比这广得多——甚至可能出现在冥王星的冰面底下。

　　What we are talking about here are the conditions that would produce reasonably complex surface creatures.) 我们在这里讨论的只是能产生比较复杂的地表生物的条件。）

　　To appreciate just how narrow, you have only to look at Venus. 若要了解幅度为何很小，你只要望一眼金星。

　　Venus is only twenty-five million miles closer to the Sun than we are. 金星离太阳只比我们近2 500万公里。

　　The Sun's warmth reaches it just two minutes before it touches us. 太阳的热量射到那里只比我们早两分钟。

　　In size and composition, Venus is very like Earth, but the small difference in orbital distance made all the difference to how it turned out. 金星的大小和结构很像地球，但是，轨道距离上的小小差别，产生了全然不同的结果。

　　It appears that during the early years of the solar system Venus was only slightly warmer than Earth and probably had oceans. 看来，只是在太阳系形成之初，金星才比地球稍稍暖和一点，而且很可能有海洋。

　　But those few degrees of extra warmth meant that Venus could not hold on to its surface water, with disastrous³ consequences for its climate. 但是，热这么几摄氏度就意味着金星无法留住表面的水，结果对气候造成了灾难性的后果。

　　As its water evaporated, the hydrogen atoms escaped into space, 随着水分的蒸发，氢原子逸入太空，

　　and the oxygen atoms combined with carbon to form a dense⁴ atmosphere of the greenhouse gas CO2. 氧原子与碳在大气里形成了厚厚的一层温室气体一氧化碳。

　　Venus became stifling⁵. 金星变得令人窒息。

　　Although people of my age will recall a time when astronomers⁶ hoped that Venus might harbor life beneath its padded clouds, possibly even a kind of tropical verdure, 我这样年龄的人还记得起，天文学家们曾一度希望，在密密的云层下面，甚至可能是在郁郁葱葱的热带植物下面，

　　we now know that it is much too fierce an environment for any kind of life that we can reasonably conceive of. 金星上存在着生命，但我们现在知道，那里的环境过于恶劣，不适与我们所能想象的任何生命。

1 assessments   

n.评估( assessment的名词复数 )；评价；（应偿付金额的）估定；（为征税对财产所作的）估价

参考例句：

• He was shrewd in his personal assessments. 他总能对人作出精明的评价。 来自《简明英汉词典》
• Surveys show about two-thirds use such assessments, while half employ personality tests. 调查表明，约有三分之二的公司采用了这种测评；而一半的公司则采用工作人员个人品质测试。 来自百科语句

2 Pluto   

n.冥王星

参考例句：

• Pluto is the furthest planet from the sun.冥王星是离太阳最远的行星。
• Pluto has an elliptic orbit.冥王星的轨道是椭圆形的。

3 disastrous   

adj.灾难性的，造成灾害的；极坏的，很糟的

参考例句：

• The heavy rainstorm caused a disastrous flood.暴雨成灾。
• Her investment had disastrous consequences.She lost everything she owned.她的投资结果很惨，血本无归。

4 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

5 stifling   

a.令人窒息的

参考例句：

• The weather is stifling. It looks like rain. 今天太闷热，光景是要下雨。
• We were stifling in that hot room with all the windows closed. 我们在那间关着窗户的热屋子里，简直透不过气来。

6 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》