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地球的年龄究竟是多少 – 译学馆
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地球的年龄究竟是多少

World’s Most Asked Questions: How Old is Earth?

每天都有超过十五亿人使用互联网 搜索各种各样的网络信息
More than 1.5 billion people use the internet every day, and they search for all kinds of stuff.
这是件好事
And good for them!
好奇心是这档科学秀栏目的核心
We’re all about curiosity here at SciShow.
正因如此 我们和谷歌以及Youtube进行合作
That’s why we’ve worked with Google and YouTube to answer ten of the most popular
回答网络搜索中十个最热门的问题
questions searched on the internet.
这就是 全球最热搜问题
This is The World’s Most Asked Questions.
今天的问题是:地球多大了?
And today’s question is: How old is Earth?
我们最新估测的地球年龄是45.4亿年
Our best estimate is that the planet is 4.54 billion years old
上下误差五千万年
give or take fifty million years.
一代代的科学家用了几百年的时间才把范围缩小到如今的水平
It’s taken scientists hundreds of years to narrow it down to that range.
但我们更想问:“地球的年龄是怎么测出来的?”
So the better question really is, “HOW do we know how old Earth is?”
在很长一段时间内 科学家仅仅在地球表面寻找最古老的区域
Well, for a long time, scientists just looked for the oldest parts of the planet’s surface
之后测定那里岩石的年龄
and then determined the age of the rocks there.
然而事实上 地球表层的板块在不停地变化
The thing is, Earth is always churning around the plates that make up its surface, forming
不断形成新的地壳 而原来的地壳便循环利用 再次进入地球内部
new crust and recycling older crust into the planet’s interior.
因此现在地表大部分的岩石平均年龄只有一亿岁
So, most rocks on the surface today are an average of 100 million years old.
但地质学家找到了年代更加久远的岩石 它们大部分曾经存在于地壳的最深层
But geologists have found older rocks, mostly those that were once in the deepest layers
但却在进入循环之前就被推出了地表
of the crust, but then got thrust upward before they could be recycled.
其中最古老的岩石是加拿大西北部发现的阿加斯塔片麻岩
The oldest of these are the Acasta Gneisses in northwestern Canada.
通过测量岩石中放射性同位素的含量 科学家们推测
By measuring the amounts of radioactive isotopes of elements in the rock, scientists were estimate
这些岩石的年龄大约是40.4亿年
their age at 4.04 billion years old.
但是 要想寻找地球上最古老的物质 就不得不提澳大利亚西部地区
But to find the oldest material of ANY kind on Earth, you have to go to Western Australia,
在那里 科学家从沉积岩中发现了锆石晶体
where geologists have discovered crystals of zircon in sedimentary rocks.
锆石中含有铀 铀会以固定、可预测的速率发生衰变
Zircon contains uranium, which decays at a fixed, predictable rate, so geologists were
因此地质学家得以确定这些晶体的年龄是43亿年
able to use that to determine that the crystals are 4.3 billion years old.
诸如此类的证据表明 地球的年龄至少有40亿年
So, evidence like this tells us that Earth must be at least four billion years old.
但在太空中 我们找到了更多的线索
But we’ve found even more clues to Earth’s age … in space.
月球的地质变化远不如地球活跃 因此我们能将月球表面物质的年龄
The moon isn’t geologically active like Earth is, so material from its surface can
推测得相当精确可靠
be dated pretty reliably.
阿波罗计划中 研究人员推测从月球带回的岩石
And the moon rocks brought back from the Apollo missions have been found to be 4.4 to 4.5
大约为44到45亿岁
billion years old.
因为月球和地球大致在同一时期内形成 这帮助我们进一步
Since the moon formed about the same time as Earth, that helps narrow down Earth’s
缩小了范围
age even further.
此外 有许多不同来源的陨石造访地球
Then there are meteorites which come from lots of different sources in space, but many
其中许多陨石都是太阳系形成之初剩余的碎片
are leftover debris from the formation of the solar system.
能够确定的是 有超过70颗陨石和月球上岩石的年龄相符
And sure enough, more than 70 meteorites have been dated to the same exact range as the
均为44到45亿年
moon rocks, 4.4 to 4.5 billion years ago.
所以当我们整合所有信息后就会发现 地球确实很古老
So you put all this evidence together, and, our little Earth is pretty old.
那么 很感谢各位的谷歌搜索 也欢迎在评论里分享你打过交道的最古老的东西是什么
So thanks for googling that, and let us know in the comments what the oldest thing you’ve
……除了地球
ever interacted with is… besides the Earth.
根据科学秀不科学的调查显示
According to our unscientific research via our SciShow survey, viewers who follow us
相比其他观众 脸书用户更有可能拥有300年以上历史的物品
on Facebook are more likely than others to own something that’s over 300 years old.
而那些拥有古董的人有更小的几率罹患经常性的呃逆[打嗝]
And those of you who own older things are less likely to get frequent hiccups.
如果你想让我们回答更多其他问题 使用标签#WMAQ 即全球最热搜问题
Let us know what other questions you’d like us to answer by using the hashtag #WMAQ, for
在月底我们会把所有这些问题
World’s Most Asked Questions, and we’ll compile the most asked questions into a video
整合到一个视频中
at the end of the month.
感谢收看本期科学秀
Thank you for watching this episode of SciShow.
如果你还有更多关于行星的问题 别忘了通过youtube.com/scishowsapce 联系我们
If you have any more planetary questions, don’t forget to check us out at youtube.com/scishowspace.

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视频概述

通过各种不同的科学研究,不断缩小范围,确定地球的精确年龄

听录译者

收集自网络

翻译译者

王梓成

审核员

萨默之光

视频来源

https://www.youtube.com/watch?v=aEucuzPvnHk

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