百科知识视频之煎蛋小学堂31 地球之水哪里来？

Unlike every other planet in our solar system,Earth's surface is 70% liquild water,Which while useful for life,is also kind of weird,because everything we know about how and when our plannet formed,says Earth's surface should be bone dry.

与太阳系的其他行星不同，地球表面的70%都是水，这对生命正合适 但也很奇怪，因为一切我们所知的地球成因及时间 都表明 地球应是极干燥的。

The story goes like this:our solar system formed from the collapse of large cloud of dust and gas.The dense blob of gas at the center ignited to form the sun,Which as a young,untable star unleashed a firrce solar wind.Over time this stream of charged particles pushed the remaining gas cloud farther and farther out,leaving only solid particles behind to clump together into rocks,planetesimals,and finally,the rocky planets of the inner solar system that we know today.

事情是这样的;太阳系由一大片尘埃和气体相撞形成。其中心最密集处开始燃烧 形成太阳，这个年轻 尚不稳定的恒星释放出了强劲的太阳风。渐渐地 带电粒子流 将剩余气体推到更远处，使剩余的固体颗粒聚集形成岩石和星子，最终便是我们今日所知的 内太阳系几颗岩态行星。

And here's the problem :water,in the from of ice,couldn't have been one of the solid particles that stuck around before our planet,because the early inner solar system was far too hot for frozen wate,and any water vapor would have been blasted away by the solar wind.

问题在此 以冰的形成出现的水，不可能是太阳系形成前的一种固体颗粒 因为早期内太阳系温度远高于冰水，任何水蒸气亦都会被太阳风吹散。

So if Earth didn't start off with water,how did we end up with such splendid oceans? We know H20 wasn't manufactured here over the eons,because natural processes like combustion,breathing and photosynthesis create and destroy roughly equal amounts of water.And either way,the amounts in question are so miniscule that they can't account for the abundance of water on the planet.

那么 地球一开始没有水 最终怎么会出现浩瀚海洋?我们知道 H20并非万千年间形成于地球，因为诸多自然过程 如燃烧，呼吸和光合作用产生并消耗着等量的水。不管怎样 它们的基数太小 不可能解释地球如此丰富的水量。

Since Earth's water was neither part of the original package nor manufactured here,It must have flown in from far away,on meteoroids or comets or other bodies originating in the outer solar system,where they were far enough from the Sun for frozen water to survive.The dirty iceballs that the we call comets are a logical candidate for the source of our water,But were ruled out when we discovered that they are far richer in heavy hydrogen than Earth water.Heavy hydrogen has a neutron as well as a proton in is nucleus,and for every million hydrogen atoms in Earth water,about 150 are heavy ones,while typical comet water has twice that many.

由于地球的水并非起源于此 或产生于此，它肯定是从远方流入的 从陨石或彗星 或者他外太阳系天体来 在那里 它离太阳够远 能让水保持冻结。那些脏冰球 即“彗星” 是水的来源的合适候选者之一。但已被淘汰 当我们发现 其重氢含量比地球上的水高得多。重氢的原子核中有一个中子和一个质子，地球水中 每一百万个氢原子中就有150个是重氢，而一般彗星水是它的两倍。

These mismatched chemical signatures suggest that Earth's water could not have arrived on comets.It turns out that the most likely source for Earth's water is a type of meteorite called a carbonaceous chondrite."Chondrite"is just the name given to the class of stony meteoroids that most commonly strike the Earth.But only the carbonaceous chondrites contain water as well as lots of carbon,if you couldn't tell from their name.

这些不相符的化学标志表明 地球的水不可能来自于彗星。结果证明 地球水最可能的来源 是一种被称为碳质球粒陨石的陨石。“球粒状陨石”只是那些常袭击地球的岩类流星体的名字。但只有碳质球粒陨石中含有水 以及大量的碳 如果你没从名字里发现的话。

They have water in then because they formed out beyond the sun's"frost line",and what's more,their water has levels of heavy hydrogen similar to that of earth water,strongly suggesting that these earth-crashers, are the source of our ice caps,clouds,rivers,and oceans.

它们含水 因为它们形成于太阳的“冰冻线”外，另外 其水中的重氢含量和地球水相似，强有力的证明了 这些地球的不速之客 是我们冰盖 云层 河流和海洋的来源。

And thus the water that turned our planet into a blue marble came,quite literally,out of the blue.

因此 把我们星球变成蓝色大理石的水也来自，文字上说是 蔚蓝深处。