[探索发现] 【整理】2014-06-29 BBC 地平线：陨石的真相-21

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 BBC: Horizon: The Truth About Meteors|  英国广播公司：地平线：陨石的真相

 

2013年2月的一个清晨，车载相机和手机捕捉到了一连串火石穿越俄罗斯乌拉尔山脉上空。随后一阵剧烈的爆炸造成了六个城市中超过1500名居民伤亡和许多房屋毁坏。据NASA的资料，这块陨石有一幢房子那么大，重约10000吨。这是1908年俄罗斯通古斯大爆炸以来穿越地球大气层的最大物体。本部纪录片，Iain Stewart教授将带领大家一起探讨陨石和流星的区别，它们来自何方？它们有什么危险？它们在地球的历史进程中扮演什么角色？

 

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原文http://www.putclub.com/html/listening/guide/2004/0509/5357.html

 

由anyawinysabrina在 整理的原文：
Comparing the effects of an airburst with a ground strike, it seems the Chelyabinsk got away lightly. It’s estimated that the largest piece to hit the ground weighed 500 kilos, a fraction of the asteroid’s original mass of 7,000 tonnes.

Now if a piece of rock that big had hit that area of Russia, it would have produced a huge impact crater. Then that kinetic energy is then delivered into the ground and we see things like seismic shock. So, you get … people would feel earthquakes on the ground.

So the fact that it was an airburst actually limited the consequences for the people on the ground. So, yes, still quite dramatic, still, you know, obviously, causing injuries. But it could have been a lot worse, had it survived down to ground.

Ground strikes are amongst the most destructive natural hazards we know of. When viewed from space, Earth’s encounters with giant asteroids in its deep history are revealed. And there is evidence from our planet’s past of a truly devastating meteorite strike that decisively altered the course of life on Earth.   

Today millions of years after the impact, the evidence for that crater is well hidden. This is a gateway to the cenotes, the unique cave system of Mexico’s Yucatan Peninsula.

yong999988

Comparing the fact of airburst with ground strike, it seems the Qilianbiesky got away lightly.It's estimated the lagest pieces to hit the ground weighted 500kilos, a fraction of  astroids with origenal mass of 7000 tons.Now we see a piece of rock that big had hit the area of Russia,and it could produce a huge impact crater.The magnentic energy are dilevered into the ground, then we see things like seismic shock, so you can get people would feel  earthquake sound on the ground.So the fact it wsn't an airburst, it limited the consequences to the people on the ground. So yes, it's still quite dramatic, still you know,often cause injuries.But it could't be lot worse had you survived out this round.Ground strikes are amongst the most destructive natural hazards we know of.When viewed from the space, Earth's encounters with giant astroids in its deep history are reviewed.And there is evidence from our planet,passed a truely devastating meteorite strikes.They decisively alter the course of life on Earth.Today, millions of years after the impact, the evidence for that crater is well hidden. This is a gateway to Senluties, the unique cave system of Mexico Ucata peninsula.