TED演讲:地球的年龄有多大(1)

 　　How old is the Earth? 地球的年龄有多大？

　　Well, by counting the number of isotopes¹ in a sample of rock that's undergone radioactive decay, 通过对岩石样品中正经历着放射衰变的同位素计数，

　　geologists² have estimated the Earth's birthday, 地质学家们已经估算出了地球的生日，

　　when it first formed from a solar nebula³, to be 4.6 billion years ago. 它从太阳星云中诞生大约是在46亿年之前。

　　But just how long is that really? 但是那到底是多久呢？

　　Here's some analogies that might help you understand. 这里有几个类比应该会帮助我们理解。

　　For example, let's imagine the entire history of Earth until the present day as a single calendar year. 例如，我们把地球到现在的整个历史想象成一个日历年。

　　On January 1st, the Earth begins to form. 在1月1号的时候，地球诞生了。

　　By March 3rd, there's the first evidence of single-celled bacteria. 到了3月3号，开始有证据证明单细胞细菌的出现。

　　Life remains⁴ amazingly unicellular until November 11th 直到10月11号之前，生物仍惊人地保持着单细胞的状态，

　　when the first multicellular organisms, known as the Ediacaran fauna⁵, come along. 这时第一种多细胞生物也就是埃迪卡拉动物群出现了。

　　Shortly thereafter, on November 16th at 6:08 p. m. is the Cambrian Explosion of life, 不久之后的11月16号下午6点08分，寒武纪生命大爆发，

　　a major milestone⁶, when all of the modern phyla started to appear. 它是一个重要的里程碑，现代生物门类开始出现。

　　On December 10th at 1:26 p. m. , the dinosaurs⁷ first evolve but are wiped out by an asteroid⁸ just two weeks later. 12月10号下午1点26分，恐龙首先发展起来，但仅仅在两周后就被一个小行星彻底抹去。

　　On December 31st, the mighty⁹ Roman empire rises and falls in just under four seconds. 12月31号，强势的罗马帝国崛起又衰落，仅仅用了4秒钟。

　　And Columbus sets sail for what he thinks is India at three seconds to midnight. 哥伦布在他认为是印度三秒到午夜的时候扬帆起航。

　　If you try to write the history of the Earth using just one page per year, 如果你想要把地球历史写下来，且一页纸便是一年，

　　your book would be 145 miles thick, more than half the distance to the international space station. 那么这本书将会有145英里（约233公里）那么厚，比我们到国际空间站的一半距离还远。

　　The story of the 3.2 million year-old Australopithecine fossil known as Lucy would be found on the 144th mile, 320万岁南方古猿化石露西的故事将在第144英里处被找到，

　　just over 500 feet from the end of the book. 仅仅还有500英尺便到了书的结尾。

1 isotopes   

n.同位素；同位素( isotope的名词复数 )

参考例句：

• the many isotopes of carbon 碳的诸多同位素
• Tritium is one of the mildest radioactive isotopes. 氚是最和缓的放射性同位素之一。 来自《简明英汉词典》

2 geologists   

地质学家，地质学者( geologist的名词复数 )

参考例句：

• Geologists uncovered the hidden riches. 地质学家发现了地下的宝藏。
• Geologists study the structure of the rocks. 地质学家研究岩石结构。

3 nebula   

n.星云，喷雾剂

参考例句：

• A powerful telescope can resolve a nebula into stars.一架高性能的望远镜能从星云中分辨出星球来。
• A nebula is really a discrete mass of innumerous stars.一团星云实际上是无数星体不连续的集合体。

4 remains   

n.剩余物，残留物；遗体，遗迹

参考例句：

• He ate the remains of food hungrily.他狼吞虎咽地吃剩余的食物。
• The remains of the meal were fed to the dog.残羹剩饭喂狗了。

5 fauna   

n.(一个地区或时代的)所有动物，动物区系

参考例句：

• This National Park is an area with unique fauna and flora.该国家公园区域内具有独特的动物种群和植物种群。
• Fauna is a biological notion means all the animal life in a particular region or period. 动物群是一个生物学的概念，指的是一个特定时期或者地区的所有动物。

6 milestone   

n.里程碑；划时代的事件

参考例句：

• The film proved to be a milestone in the history of cinema.事实证明这部影片是电影史上的一个里程碑。
• I think this is a very important milestone in the relations between our two countries.我认为这是我们两国关系中一个十分重要的里程碑。

7 dinosaurs   

n.恐龙( dinosaur的名词复数 )；守旧落伍的人，过时落后的东西

参考例句：

• The brontosaurus was one of the largest of all dinosaurs. 雷龙是所有恐龙中最大的一种。 来自《简明英汉词典》
• Dinosaurs have been extinct for millions of years. 恐龙绝种已有几百万年了。 来自《简明英汉词典》

8 asteroid   

n.小行星；海盘车(动物)

参考例句：

• Astronomers have yet to witness an asteroid impact with another planet.天文学家还没有目击过小行星撞击其它行星。
• It's very unlikely that an asteroid will crash into Earth but the danger exists.小行星撞地球的可能性很小，但这样的危险还是存在的。

9 mighty   

adj.强有力的；巨大的

参考例句：

• A mighty force was about to break loose.一股巨大的力量即将迸发而出。
• The mighty iceberg came into view.巨大的冰山出现在眼前。