一些科学家假定，小行星撞击地球导致了恐龙的灭绝。
Some scientists hypothesize that the extinction of the dinosaurs resulted from the effects of an asteroid collision with Earth.
会不会发生小行星撞击地球的事件呢？
假如小行星撞击地球，它们的平均撞击速度将达到30公里每秒。
If an asteroid hit Earth, it's average speed would be 30kilometers per second.
举例说，若有政客提议进行一场防范小行星撞击地球的行动，那他将会被人讥笑，还有可能落选。
A politician who proposed a campaign of preventing asteroid collisions with Earth, for example, would be ridiculed and probably voted out of office.
白垩纪末期，当小行星撞击地球使得地表上的光合作用停止。生长速度较快的恐龙无法在这场危机中幸免于难。
Fast-living dinosaurs were unable to survive the crisis at the end of the Cretaceous, when an asteroid hit Earth and brought photosynthesis to a halt.
在大概6500万年前——正如我们已经知道的那样——小行星撞击地球，带了云层阻挡住了太阳使得地球降温。
Some 65 million years ago — as we've all come to know — an asteroid struck the earth, sending up a cloud that blocked the sun and cooled the planet.
比如，白垩纪至第三纪所发生的大灭绝。当时，可能由于一颗小行星撞击地球，恐龙和众多同时代的物种都灭绝了。
An example is the KT Mass Extinction when the last dinosaur and ammonite species, among others, became extinct, perhaps as a result of an asteroid striking the Earth.
如果一个100英尺直径的小行星撞击地球，它在大气中爆炸产生的冲击波可以令数百平方英里内所有的树木倒伏，并杀死所有的大型动物。
If a 100-foot-wide asteroid hit Earth, the shock wave from its explosion in the atmosphere could flatten trees and kill every large animal for hundreds of square miles.
尽管白垩纪时小行星撞击地球后为哺乳动物搭起了活动的舞台，但是哺乳动物真正大行其道是100万年以后的事情了，也就是在始新世时期。
Though the Cretaceous asteroid cleared the stage, mammals did not really get going until 10m years later, in the Eocene epoch.
但是据进一步的观察，阿波菲斯小行星撞击地球的威胁程度评估被降低，现在的预测，这颗直径为270米的空间岩石在2029年撞击地球的可能性为零。
After further observations, the threat of an Apophis impact was lowered, and now the chance of the 270 meter space rock hitting us in 2029 is zero.
多国科学家组成的科研小组将对墨西哥尤卡坦半岛著名的“奇科苏卢布”陨石坑进行声波探测，而这个巨大的陨石坑可能就是6500万年前造成恐龙灭绝的根本原因。 科学家们希望通过这一研究能找到当时彗星或小行星撞击地球的更多的有用信息。
Scientists working off the Yucatan Peninsula are preparing to use sound waves to search for information about an asteroid that may have wiped out the dinosaurs 65 million years ago.
据西班牙巴利亚多利德大学(UVA)德玛丽亚·尤金·尼亚•珊萨图丽欧(maria Eugenia Sansaturio)介绍：“(101955)1999 RQ 36小行星撞击地球的总的概率估计为0.”00092，即大约千分之一。
The total impact probability of asteroid '(101955) 1999 RQ36' can be estimated in 0.00092.
如果这是由行星撞击所形成，毫无疑问，它将是地球上最大的陨石坑。
If that turns out to be from an asteroid impact, it would be the largest crater found on Earth. Ever.
有一些还未被美国宇航局近地天体计划发现的小行星，很有可能会撞击我们的地球，一个被称为1950DA的现象很有可能在2880年出现。
None of the objects yet discovered by NASA's Near earth objects program have a high probability of hitting the earth — though one known as 1950 DA will come extremely close in 2880.
但是经过更多的观察和一数字演算之后，天文学家注意到这个行星在2029年撞击地球的可能性微乎其微。
A few additional observations and some number-crunching later, astronomers noted that the chance of the planet-killer hitting Earth in 2029 was nearly zilch.
据最近的伊卡璐斯日报（Icarus）报道，这次通过两个数学模型来评价小行星在22世纪撞击地球的几率。
Recently published in the journal Icarus, this impact probability was calculated using two mathematical models to assess potential threats to Earth in the 22nd Century.
这个理论认为，在早期的时候，地球曾经被一颗火星般大小(相当于地球体积的一半)的行星撞击。
An object about the size of mars-half the size of earth-slammed into our planet very early in its formation, the theory says.
另外，这还表明地球上的生命可能会经由撞击产生的碎屑降落到其他行星或者卫星，当然它们能否在这些天体上生存就是另一回事了。
Alternatively, it suggests life from Earth may have landed on other planets or moons on boulders blasted off Earth in an impact, though whether it could survive on those bodies is another matter.
不过，它仍然存在一个微小的机会可能在2036年或2068撞击地球，这取决于这颗小行星在未来经过地球时的确切路线。
However, there's still a tiny chance it will hit in 2036 or 2068-depending on the exact route the asteroid follows during its next pass near Earth.
许多科学家认为，地球遭受小行星或彗星的直接撞击可能是恐龙灭绝的原因。
Many scientists believe the Earth suffered a direct hit from an asteroid or that a comet could be to blame for the extinction.
在那段时期的中间，也就是三叠纪时期，一颗小行星撞击了地球。
About halfway through that period, known as the Triassic, an asteroid struck Earth.
这样大小的小行星造访地球基本六年左右一次，也有小概率会撞击地球。
Asteroids of this size pass close by Earth every six years or so, and there's a small chance one could hit Earth.
在2004年的时候，美国航空航天局的科学家们宣布阿波菲斯这个比两个足球场还大的小行星，可能会在2029年撞击地球。
In 2004, NASA scientists announced that there was a chance that Apophis, an asteroid larger than two football fields, could smash into Earth in 2029.
当俄国最近又预测阿波菲斯99942可能于2036年4月13日撞击上地球时，该小行星再次引起媒体关注。
The asteroid hurtled back into the news when Russia recently predicted 99942 Apophis may hit Earth on April 13, 2036.
美国国家航空和宇宙航行局在很大程度否定了一份俄国的报告，该报告称一个比两个足球场还大的行星可能于2036年撞击地球。
NASA has largely dismissed a Russian report that an asteroid larger than two football fields could hit Earth by 2036.
据估算，地球范围150英尺之内有500 000颗小行星，撞击地球的概率约为300年一次。
There are an estimated half a million asteroids in the 150-foot range, which strike Earth roughly once every 300 years.
如果你在为小行星会不会撞击地球而忧心忡忡，那么你应当清楚这样一个事实：由于地球引力而引发的小行星撞击，就好比飞驰的卡车，车头前面的格栅总是在不断吞噬着迎面扑来的飞虫。
If you happen to live in fear of asteroids, then here's a sobering fact for you: Our planet absorbs asteroid impacts like a truck grille eats bugs.
造成这场全球灾难的真正原因是，大约6,500万年前，一群小行星——而不是一颗孤立的天体——密集地撞击了地球。
What it does do is make the case that Earth was hit by an asteroid shower around 65 million years ago, rather than a single space rock.
造成这场全球灾难的真正原因是，大约6,500万年前，一群小行星——而不是一颗孤立的天体——密集地撞击了地球。
What it does do is make the case that Earth was hit by an asteroid shower around 65 million years ago, rather than a single space rock.
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