标签：陨石的真相 相关文章
When you consider the Earths history stretching over billions of years, its clear that meteorite impacts, far from being unexpected, are just a normal part of the life cycle of our planet. But that is not how they seem to us. The Chebarkul meteorite
探索与发现2014年
Comparing the effects of an airburst with a ground strike, it seems the Chelyabinsk got away lightly. Its estimated that the largest piece to hit the ground weighed 500 kilos, a fraction of the asteroids original mass of 7,000 tonnes. Now if a piece
探索与发现2014年
There it is! Yep. Its about 90 kilometres up, at that stage, travelling at 17.5 kilometres per second. Using the different camera positions, scientists have pinpointed the exact position at which the meteor entered the atmosphere. And by tracking the
探索与发现2014年
So was this a near miss for us? If the asteroid had been in a different part of its orbit, so it didnt hit this year but it hit next year, it would have still hit us on February 15th. But instead of coming in over Russia, it would have come in over t
探索与发现2014年
On June 30th, 1908, a huge explosion tore through the forest of Tunguska, Siberia. It was 20 years before the Russians mounted an expedition to the site. What they found astonished them. 60 million trees across an area the size of London had been lev
探索与发现2014年
Most of the damage from an explosion like this is actually the blast wave. Its the very high winds. Mark created a simulation to see what size an asteroid would need to be to be able to generate such destructive power. In this simulation I include mo
探索与发现2014年
Really, its a balance between the size of the object, its speed into the atmosphere and critically the altitude at which it explodes. Too high, if its too small and it explodes too high, the shockwave has little effect on the ground. If its quite low
探索与发现2014年
Down on the ground, the scale of impact is even more breathtaking.The crater is more than 1000 meters across and nearly 200 meters deep.The forces here were enoumous.The impact on this solid rock into this pulverized mochi,just bustled in your hand.Y
探索与发现2014年
As the divers have explored further, they discovered the Siluteis are actually part of a huge complex of tounels and caves.In fact, when you look from above, you can see Senluties scattered across hundreds of kilometers.And when they were mapped, it
探索与发现2014年
The meteorite was 15 kilometres across, enough to cause utter devastation across the whole planet. It exploded with a force of 100 million million tones of TNT. The blast sent a giant plume of vaporized rock out into space. A crater was punched 30 ki
探索与发现2014年
Tim has developed a map to visualize their location. And on that map, the most important are the Near-Earth asteroids, the ones closest to the planet. On the screen here is a map of the solar system. And Ive got the Sun in the centre and the third pl
探索与发现2014年
Weknew from the radar measurements where Golevka was within a few tens of metres.And yet it was actually 12 or 15 kilometres away from where it was predicted tobe without Yarkovsky effect. So these very precise radar observations allowedus to see the
探索与发现2014年
Heset out to investigate a hundred-year-old theory that said asteroids werepowered by the Sun itself. It was called the Yarkovsky effect. The Yarkovskyeffect is a very small acceleration and acts on asteroids and what it is is ifyou take a model, the
探索与发现2014年
Itsremarkable how we are able to build up this picture of whats going on millionsof miles away in the solar system. Its one of the joys of science really, justalmost like a detective picking up on those tiny clues to tell a bigger story. Sothat the b
探索与发现2014年
For the residents of the Russian city of Chelyabinsk, the morning of Friday, February 15, 2013 began like any other. As they set off to work in what has become a craze throughout Russia, many recorded their journeys, but these cameras usually used fo
探索与发现2014年
This isnt the first time its happened. Over thelast few years, scientists have examined many other devastating impacts in theEarths past. Using this knowledge, I want to answer the key questions that theChelyabinsk meteor strike raises. Where did thi
探索与发现2014年
I was shocked. I was truly shocked. I never thought Iwould see an event like this over a major city during my lifetime. We couldnt predict this was going to happen. The pieceof rock that actually entered the atmosphere was relatively small, maybe onl
探索与发现2014年
Amazing images. But what can you get out of these asan expert? What it shows us, first of all, is a great record ofthe entry of the object into the Earths atmosphere. So you see it right fromthe moment it really penetrated. And there it is. That is t
探索与发现2014年
The explosion generated a shockwave so massive it wasdetected over 15,000 kilometres away. The low-frequency waves were picked up bymonitoring stations. So it is kind of like a listening network around theworld. Thats right. Theyre not set up for fir
探索与发现2014年
Meteor strikes as big as this may be rare butscientists have a surprisingly detailed knowledge of what meteorites are andwhere they come from. Long before the meteorite reached its explosivefinale in full view of Chelyabinsks dash cams, it had a very
探索与发现2014年