到底要多大的小行星才能将这么多铱散布在整个星球上？

　　And they come up with a very rough number of something on the order of ten kilometers across, that's, you know, it's Mount Everest size sort of impact, if you will.

　　他们提出了一个粗略的数据，大概是10千米直径的东西，要知道这大小可是相当于埃佛勒斯峰了。

　　But if an asteroid the size of Mount Everest destroyed the dinosaurs, where was the crater?

　　不过要是埃佛勒斯峰那么大的小行星毁灭了恐龙，那陨石坑在哪里？

　　e12a5.jpg

　　For ten years, the mystery remained.

　　十年间谜团依旧。

　　Then, in 1990, a clue emerged.

　　之后，在1990年一条线索浮现了。

　　Searching for oil in the Yucatan peninsula, geologists came upon an evidence of a massive underwater impact.

　　在尤卡坦半岛进行石油勘探时，地质学家们发现了一个巨大的水下冲击的证据。

　　There was an oil company in Mexico, searching for different places where there might be oil deposits.

　　在墨西哥有一家石油公司，在不同地方寻找可能储藏石油的地方。

　　And in those areas they actually found a fairly circular feature, and in that, they deduced that that might be an impact crater.

　　他们在那些区域发现了相当圆的地形，就这样他们推测那可能是个撞击坑。

　　The satellite images were mind boggling.

　　卫星图像更是让人震惊。

　　And then they started to see the telltale signs that something very big and very large had hit.

　　在那时他们开始看到一些能说明问题的迹象，地球被非常巨大的物体击中过。

　　And now finally, what's happened just recent times, is we have radar information from the Space Shuttle, and from that you can actually see the outlines, very faintly, of this impact crater.

　　现在终于，在不久之前从航天飞机上获得了雷达信息，从上面能够隐约看到这个撞击坑的轮廓。

　　This huge crater is called the Chixalube crater.

　　这个巨大的陨石坑被称作奇科苏卢布陨石坑。

　　It needed to be the right size to be linked to the K-T boundary evidence.

　　要与KT界限层的证据连接起来，它的大小必须合适。

　　It wasn't until 1990,1991 when the Chixalube crater in Northern Yucatan was identified.

　　直到1990年、1991年，尤卡坦半岛北部的奇科苏卢布陨石坑才被发现。

　　Most people felt pretty confident that, that crater was 180 kilometers across based on the most prominent set of circular features there.

　　多数人很确信，那个陨石坑直径达180千米，这是据最主要的一层环状结构测量所得。

　　A 180 kilometer crater, that's 111 miles across.

　　180千米的陨石坑，就是直径111千米。

　　Looking backwards, what size asteroid could create a crater of that magnitude?

　　反过来看看，多大的小行星才能产生如此规模的陨石坑呢？

　　So how big an impactor would it take to make a 180-kilometer diameter crater on the earth?

　　多大的撞击物才能在地球上留下直径180千米的陨石坑呢？

　　Well, at the typical speeds that asteroids will strike the earth you know, of order 20 kilometers per second, the answer comes back an asteroid, you know,

　　小行星撞击地球的典型速度是每秒20千米，答案回到一个直径大约10千米小行星，

　　about ten kilometers across and that's perfectly consistent with the original estimate from the concentration of Iridium that the Alvarez's independently calculated a decade previously.

　　那与原始的估计完美地一致，原始的估计来自阿尔弗雷兹十年前对铱含量的独立计算。

　　This evidence was overwhelming.

　　这是压倒性的证据。

　　An asteroid about the size of Mount Everest, had struck the earth in the Yucatan Peninsula at the end of the Cretaceous period, 65 million years ago.

　　大小如同埃佛勒斯峰的小行星，在六千五百万年前白垩纪末期于尤卡坦半岛撞击到地球上。

　　Dr. William Bottke, assistant director of space studies at the Southwest Research Institute, then went even further.

　　威廉·波特克博士是西南研究院太空研究部的助理主任，他的研究更进一步。

　　His research pointed to the Baptistina asteroid fragments, from the deep space collision 250 million years earlier.

　　他的研究指向巴蒂斯缇娜小行星碎片，它们来自此前两亿五千万年前的深空撞击。

　　And it showed that the earth wasn't Baptisina's only victim.

　　而且有证据表明地球不是巴蒂斯缇娜的唯一受害者。

　　An asteroid also struck the moon, triggering a landslide.

　　一颗小行星也撞到了月球，导致了山崩。

　　The Apollo 17 spacecraft, landed in a place, where they actually detected evidence for a landslide that had happened about 110 million years ago.

　　阿波罗十七号宇宙飞船，在降落位置探测到了山崩的证据，发生的时间是一亿一千万年前。

　　They believe this landslide was triggered by a cratering event on the other side of the moon.

　　他们相信这次山崩是月球另一侧一次撞击事件所导致的。

　　Not only it's very large, it's well over 80 kilometers or so, but it's also surprisingly young, it would have this age of 110 million years.

　　它不仅非常大，直径达约80千米，而且年轻得惊人，其年龄仅仅为一亿一千万年。

　　We find there's a very high probability, well over 70%, that this particular crater, was produced by the Baptistina fragments.

　　我们发现有很大可能，超过百分之七十，这个陨石坑是巴蒂斯缇娜碎片造成的。

　　An asteroid storm blasted the solar system.

　　一次小行星风暴轰击太阳系。

　　One struck the moon.

　　一颗击中月球。

　　Another was on a collision course with prehistoric earth with horrifying results.

　　另一颗的轨道与史前地球交汇带来可怕的结果。

　　Traveling at twice the speed of sound, an enormous asteroid made its way into our inner solar system, on a collision course with the dinosaurs.

　　一颗巨大的小行星以音速两倍的飞行速度，迎头闯进我们的内太阳系，将要撞击到恐龙的世界。

　　65 million years ago, the earth suffered an enormous extinction event, one that would wipe out all the non-avian dinosaurs, along with millions of other life forms.

　　六千五百万年前，地球遭受了一次重大灭绝事件，这次灭绝事件消灭了所有的非鸟类恐龙，以及数百万其他生物。

　　Imagine a rock, the size of Manhattan Island, slamming into the earth at 43,000 miles per hour.

　　想象一下一块像曼哈顿岛一样大的石头，以时速近43,000英里撞到地球之上。

　　You've heard of the phrase hell on earth?

　　听说过人间地狱吗？

　　This impact was so powerful hell would have felt like a tanning booth in comparison.

　　这次撞击力量太强大，地狱与之相比就像是小儿科。

　　In 2000, another link was found between the asteroid and prehistoric earth.

　　在2000年，小行星和史前地球的另一个联系也被发现了。

　　Several years ago, there was a service, they went out, and actually took cores, from different places in the ocean.

　　几年前，曾有过一些调查，人们在大洋的不同位置，进行岩芯采样。

　　And they tried to probe, to get, these cores all way back to 65 million years ago.

　　他们试图探测获得六千五百万年前的岩芯。

　　And interesting enough in one of these probe, in one of these core samples, they found a tiny piece of a meteorite, a fossil meteorite.

　　在这些探测中非常有趣的是，在一个岩芯样本里他们找到了一小块陨石，化石陨石。

　　And the composition of that meteorite, is very consistent with the composition of Baptistina.

　　那个陨石的成分，与巴蒂斯缇娜其实非常一致。

　　So, it's not just dynamics, but it's also this link, with the chemistry.

　　所以不仅有动力学证据，在化学成分上也有联系。

　　The impact of the asteroid would kick start a series of cataclysmic events that would devastate life on earth.

　　小行星的撞击会引发一系列灾难事件，重创地球上的生命。