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.
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.
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.
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.
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.
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.
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.
也许还可能解释这样的事实，那就是在过去大约1亿年间，撞击地球的小行星的数量是原来预计的两倍。
They are probably also the explanation for the fact that, over the past 100m years or so, the number of asteroids that have hit the Earth is about twice that which would have been expected.
在接下来的1.35亿年里，这些大蜥蜴开始统治地球，直到一个小行星撞击在尤卡坦半岛。
For the next 135 million years, the great lizards ruled Earth. Then an asteroid struck the Yucatan Peninsula.
原宇航员RustySchweickart说道。 他是B612基金会的共同发起人，该组织致力于保护地球免受小行星的撞击。
“You’re moving the largest mother lode imaginable ” said former astronaut Rusty Schweickart cofounder of the B612 Foundation an organization dedicated to protecting Earth from asteroid strikes.
问题是现在还有代号为1999RQ36小行星这个更大的“潜在威胁”，它有千分之一的较高概率会撞击地球，时间很可能是2182年。
Now we have 1999 RQ36, a bigger "potentially hazardous" asteroid, with a higher one-in-a-thousand chance of striking Earth in 2182.
如果Bbylev的预测成真而且地球能侥幸逃脱，那她对结实的小行星撞击，太阳风暴或者人类的工程灾难来临还有一丝喘息的机会。
If Bobylev's prediction holds and Earth escapes unscathed, it will catch a bit of a breather barring the oddball asteroid, solar storm or human-engineered disaster.
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.
7千米直径（2.9英里）的小行星的撞击在地球上造成了90千米直径（55.9英里）的火山口，位于澳大利亚南部Gawler Ranges 的Acraman湖。
The 4.7-kilometer (2.9-mile) asteroid left a 90-kilometer (55.9-mile) crater in what is now Lake Acraman in the Gawler Ranges of South Australia.
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.
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.
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.
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.
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.
有一些地质学家则主张，地球当时是被一颗巨大的小行星所撞击——规模小于6500万年前造成恐龙灭绝的撞击。
Some geologists have argued that the world was hit by a giant asteroid - a smaller version of one which wiped out the dinosaurs 65million years ago.
有一些地质学家则主张，地球当时是被一颗巨大的小行星所撞击——规模小于6500万年前造成恐龙灭绝的撞击。
Some geologists have argued that the world was hit by a giant asteroid - a smaller version of one which wiped out the dinosaurs 65million years ago.
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