爆炸可能使陨石汽化了。
我们从流星体中得到流星和陨石。
他们找到了一块重逾一万亿吨的陨石。
They located a meteorite with a mass of over a trillion tons.
这个想法并不是说这些构件只是陨石上的乘客。
The idea isn't that these building blocks are just passengers aboard meteorites.
"在二十世纪，已知有两次大型陨石与地球相撞的案例。
Twice in the twentieth century, large meteorite objects are known to have collided with Earth.
科学家将白垩纪末期的大灭绝与地球上的陨石撞击联系起来。
Scientists have linked the mass extinction at the end of the Cretaceous with a meteorite impact on Earth.
但是，这使得我们更容易将东西识别为陨石，而不仅是地面的岩石。
But that makes it easier to identify something as a meteorite, as opposed to just a terrestrial rock.
铱存在于陨石和火山物质中，但在火山物质中同时包含高浓度的镍和铬。
Iridium occurs in meteorites and volcanic material, but in the latter case it is accompanied by elevated levels of nickel and chromium.
进行这项研究的小组通过详细分析得出结论：陨石的撞击确实是危险的。
The group conducting the study concluded from a detailed analysis that impacts from meteorites can indeed be hazardous.
即使是现在，微小的陨石仍在不断地撞击地球，然后落到陆地上和大海中。
Even today, microscopic meteorites continually bombard Earth, falling on both land and sea.
人们发现，在一些保存着太阳系原始化学成分的陨石中，铱元素的含量很高。
Ir is found in high concentrations in some meteorites, in which the solar system's original chemical composition is preserved.
为了比较陨石和太阳的成分，我们需要利用元素的比率，而不单单是原子的丰度。
To compare the compositions of a meteorite and the Sun, it is necessary that we use ratios of elements rather than simply the abundances of atoms.
几天后，他收集了落在冰冻湖面的陨石的原始样本，并把它们储存在他的冰箱里。
He collected pristine samples of the meteorite just days after they fell on the frozen lake, and stored them in his freezer.
这一沉积层富含稀有金属铱，以及其他在陨石中较丰富而在地壳中十分罕见的元素。
This sediment layer is enriched in the rare metal iridium and other elements that are relatively abundant in a meteorite but very rare in the crust of Earth.
从理论上讲，细菌可能是在火星的早期发展起来的，其中一些是由陨石带到地球的。
It is theoretically possible that bacteria developed on Mars early in its history and that some were carried to Earth by a meteorite.
陨石的撞击代表了一种可能导致全球性灾难并严重影响地球上所有生命进化的机制。
Impacts by meteorites represent one mechanism that could cause global catastrophes and seriously influence the evolution of life all over the planet.
越来越多的证据表明，陨石的撞击对地球产生了重要的影响，特别是在生物进化领域。
There is increasing evidence that the impacts of meteorites have had important effects on Earth, particularly in the field of biological evolution.
我将介绍陨石的不同类型，以及我们能够从中了解到的有关地球和太阳系的形成的知识。
I wanna go over the different types of meteorites, and what we've learned from them about the formation of Earth, and the solar system.
无线电开始传输大量信息，都是关于卫星的轨道路径、探测到的辐射量以及陨石的存在的。
Its radio begins to transmit an astonishing amount of information about the satellite's orbital path, the amount of radiation it detects, and the presence of meteorites.
陨石的撞击对某些物种是有利的，它们会茁壮成长；而对其他物种则是灾难性的，它们会灭绝。
Meteorite impacts can be advantageous for some species, which thrive, and disastrous for other species, which become extinct.
阿连德陨石被归类为球粒陨石。
在火星上，直径小于5公里的陨石坑相对较少。
On Mars, there are relatively few craters less than 5 kilometers in diameter.
然而，火星陨石坑被填满的速度比月球陨石坑快很多。
However, Martian craters get filled in considerably faster than their lunar counterparts.
这个陨石坑现在深埋在沉积物中，最初直径约200公里。
The crater, now deeply buried in sediment, was originally about 200 kilometers in diameter.
根据无线电测量数据，我们可以得知盆地里有许多较小的陨石坑。
From radio survey data, we know that the basin contains lots of smaller craters.
这使它成为太阳系中已知最大的陨石坑，也可能是最古老的陨石坑。
That makes it the biggest known crater in our solar system and it may well be the oldest.
这样大小的小行星即使受到冲击碎裂之后也会留下一个巨大的陨石坑。
An asteroid of this size would be expected to leave an immense crater, even if the asteroid itself was disintegrated by the impact.
即使被从陨石坑中挖掘出的陆地物质稀释，这种陨石成分也很容易识别。
Even diluted by the terrestrial material excavated from the crater, this component of meteorites is easily identified.
和在月球的一样，大型撞击陨石坑的范围之广可以显示出火星表面的年龄。
As on the Moon, the extent of large impact cratering serves as an age indicator for the Martian surface.
然而，火星上的喷出物则由于那些溅出或溢出陨石坑的液体而令人印象深刻。
However, the ejecta on Mars gives the distinct impression of a liquid that has splashed or flowed out of crater.
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