关于地球你需要知道的一切：英语精读讲义

Planet Earth is the home of every life form known to us in the universe. 短語搭配

地球是宇宙中已知的所有生命形式的家园。

Its age is about a third of the age of the universe 語法

它的年龄大约是宇宙年龄的三分之一，

and admit it it is a thing of beauty. 語氣意圖

而且承认吧，它真的很美。

A slightly squashed sphere with a heavy metal core and a lighter surface crust

它是一个略微扁平的球体，拥有重金属内核和较轻的表面地壳，

wrapped in a thin sliver of sweet air to breathe 講解

被薄薄一层供呼吸的甜美空气包裹着，

with vast oceans, fertile plains, magnificent mountains,

有着浩瀚的海洋、肥沃的平原、雄伟的山脉、

fresh water rivers, streams, lakes and aquifers

淡水河、溪流、湖泊和蓄水层，

orbiting a star which warms us and gives us energy.

围绕着一颗为我们提供温暖和能量的恒星运行。

But how did our home come into existence 短語搭配

但是，我们的家园是如何诞生的？

and what's it made of? 短語搭配

它又是怎样构成的？

4.6 billion years ago,

46亿年前，

Earth was created from the remnants of dead stars 用詞

地球由死亡恒星的残骸孕育而成，

that collected in a giant dirty gas cloud.

这些残骸聚集在一团巨大的尘埃气体云中。

The gas cloud became denser in its center and formed an accretion disk. 用詞

气体云的中心变得越来越致密，并形成了一个吸积盘。

Small particles started clumping together and building larger and larger objects 語法

细小的颗粒开始聚集成团，形成越来越大的物体，

until they formed the objects we call planets today.

直到它们形成了今天我们称之为行星的天体。

This process took 10 to 20 million years and is still not very well understood. 語法

这个过程耗时1000万到2000万年，且至今尚未被完全弄明白。

At about this time when the solar system was young and chaotic,

大概就在这个太阳系还处于年轻且混乱的时期，

a giant object about as big as Mars collided with our home. 語法

一个约有火星那么大的巨大天体撞击了我们的家园。

The impact was violent

撞击非常猛烈，

and if the object had been more massive, 語法

如果那个天体再大一点，

it might have destroyed Earth.

它可能就把地球给毁灭了。

Material from Earth was smashed out into orbit and formed the Moon,

地球的物质被撞飞到轨道上，形成了月球，

which is the biggest satellite in relation to its planet in the solar system. 短語搭配

相对于它所环绕的行星而言，它是太阳系中最大的卫星。

At this time, Earth was a hot hell,

那时的地球如同一个炽热的地狱，

constantly being hit by asteroids with seas of lava and a toxic atmosphere.

不断遭到小行星的撞击，到处是岩浆的海洋和有毒的大气。

But something was about to change drastically. 語法

但有些事情即将发生剧变。

Earth cooled down.

地球冷却了下来。

Water from the inside of the Earth wandered to the surface and rained down on Earth,

地球内部的水向地表游移，并以降雨的形式落到地球上，

only to vaporize again and become clouds. 語法

接着再次蒸发成为云层。

Millions of asteroids brought more and more water to our planet.

数以百万计的小行星为我们的星球带来了越来越多的水。

All the water on Earth has about this volume compared to Earth.

地球上所有的水加起来，与地球相比大约是这个体积。

Today, the surface of Earth is 71% water and 29% land.

今天，地球表面71%是水，29%是陆地。

97.5% is saline water,

97.5%是咸水，

while only 2.5% is fresh water.

而只有2.5%是淡水。

The fresh water is 69% ice and snow,

在淡水中，69%是冰雪，

30% are ground waters,

30%是地下水，

and only about 1% make up the remaining ground waters. 短語動詞

仅有约1%构成了剩余的地下水。

But even this small part is mostly frozen.

但这极小的一部分水大部分也是冰冻的。

Only a tiny part of our water is actually lakes and rivers,

实际上，我们的水中只有微乎其微的一部分是湖泊和河流，

and an even tinier part is bound in living things.

更小的一部分存在于生物体内。

So, gradually the Earth cooled down

于是，地球逐渐冷却下来，

and the surface formed a thin crust.

表面形成了一层薄薄的地壳。

But inside the Earth,

但在地球内部，

hot rock continued to swirl about, moving the crust from below and breaking it apart. 短語動詞

炽热的岩石不断翻滚，从下方推动地壳并使其断裂。

This process is called plate tectonics and is happening right now. 用詞

这个过程被称为板块构造，而且此刻正在发生。

We'll make a whole video about it in the future.

将来我们会专门做一整期视频来讲解它。

For now, let's just say that the crust of Earth 表達脈絡

现在，我们只需知道地球的地壳

consists of separate giant plates that move around. 短語搭配

是由四处移动的独立巨大板块组成的。

As they meet, they crumble and create mighty mountains

当它们相遇时，会相互挤压并隆起雄伟的山脉，

or violently plunge back down deeper into Earth,

或者剧烈地重新沉入地球深处，

creating deep trenches.

形成深邃的海沟。

That's the way the highest place on Earth was formed,

地球上的最高点就是这样形成的，

Mount Everest, and the deepest, the Mariana Trench. 語法

即珠穆朗玛峰，还有最深处的马里亚纳海沟。

From our perspective, Earth's mountains and trenches are mighty indeed, 表達脈絡

从我们的视角来看，地球上的高山和海沟的确雄伟，

but when you look at the Earth in cross-section,

但当你观看地球的剖面图时，

you can see how tiny they actually are.

你就会发现它们实际有多么微不足道。

The part we stand on is the crust,

我们所站立的部分是地壳，

which is about 50 km thick,

它的厚度约为50公里，

though it can vary between 5 and 70 km.

不过它可以在5到70公里之间变化。

By the way, the deepest hole ever drilled by man is 12.262 km deep.

顺便说一句，人类钻出的最深的洞深达12.262公里。

After the crust comes the mantle. 語法

地壳之下是地幔。

It's a silicate rocky shell and about 2,900 km thick.

它是一层硅酸盐岩石壳，厚约2900公里。

The mantle consists of the upper mantle and the lower mantle.

地幔由上地幔和下地幔组成。

The upper mantle has different regions too.

上地幔也有不同的区域划分。

Its upper part,

它的上部，

which is viscous and carries the crust,

也就是具有黏性并承载着地壳的部分，

is called the lithosphere.

被称为岩石圈。

After that, there comes the asthenosphere,

在它下面的是软流圈，

which consists of less mobile, mostly solid material.

主要由流动性较低、大体呈固态的物质构成。

The lower mantle reaches deep down to the outer core of Earth.

下地幔一直向下延伸至地球的外地核。

Earth's outer core is a liquid layer of iron and nickel

地球的外地核是一层液态的铁和镍，

about 2,266 km thick.

厚约2266公里。

Temperatures vary from 4,000 °C to 5,700°C. 短語搭配

温度从4000°C到5700°C不等。

And in the center is the inner core.

在中心的是内地核。

It's mostly solid,

它主要是固态的，

a ball made of an iron-nickel alloy with a radius of about 1,200 km,

是一个由铁镍合金构成的球体，半径约为1200公里，

70% of the size of the Moon,

大小相当于月球的70%，

and about the temperature of the surface of the Sun.

温度与太阳表面差不多。

It is slowly growing at an estimated rate of about 1 mm per year. 短語搭配

它正在以每年约1毫米的估计速度缓慢增长。

Now, for some perspective. 表達脈絡

现在，让我们换个角度看看。

This small layer of crust

这一小薄层的地壳，

crystallized melt products of former molten mantle

即曾经熔融的地幔所结晶出的熔体产物，

is where we live.

就是我们居住的地方。

Then, there's Earth's magnetic field.

接下来是地球的磁场。

It's an invisible phenomenon that diverts high energy particles coming from the Sun and other sources,

这是一种无形的现象，能偏转来自太阳和其他高能粒子流，

allowing for a stable environment 短語動詞

从而提供一个稳定的环境，

with comparatively little radiation impact on Earth.

让地球受到辐射的影响相对较小。

But why is it there?

但它为什么会存在呢？

Actually, we don't really know a terrible lot about that. 語氣意圖

事实上，关于这一点我们并不十分清楚。

We know it has something to do with the core of the Earth. 短語搭配

我们知道它与地球的核心有关。

Inside this metal sphere,

在这个金属球体内部，

large electrical currents flow in complicated patterns.

巨大的电流以复杂的模式流动。

They cause a magnetic field that sort of stabilizes itself 語氣意圖

它们根据电动力学定律，

according to the laws of electrodynamics.

产生了一个能够自我稳定的磁场。

This entire system is called the dynamo.

整个系统被称为发电机效应。

But don't let us fool you into thinking we have it all figured out. 講解

但别被我们骗了，别以为我们已完全弄懂了这一切。

Speaking of breathtaking information, what about the airy stuff that surrounds us? 講解

说到令人惊叹的信息，那环绕着我们的空气又如何呢？

By volume, dry air consists mostly of nitrogen, 用詞

按体积计算，干燥的空气主要由氮气、

oxygen, argon, carbon,

氧气、氩气、碳、

a variable amount of water vapor, 短語搭配

数量不等的水蒸气，

and small amounts of other gases.

以及少量其他气体组成。

Humans are very dependent on the lowest layer of the atmosphere,

人类非常依赖大气层的最底层，

the troposphere, where the weather is.

即对流层，也就是产生天气的地方。

It's 12 km thick on average. 短語搭配

它的平均厚度为12公里。

Above that is the stratosphere, 語法

之上是平流层，

which is where the ozone layer protects

那是臭氧层所在之处，它保护着

us from the Sun's most aggressive type of light.

我们免受太阳最强烈光线的伤害。

Above that is the mesosphere,

再往上是中间层，

the coldest place on Earth with an average temperature around -85°C.

它是地球上最冷的地方，平均温度约为-85°C。

At about 80 km up, the thermosphere starts.

在80公里左右的高空，热层开始出现。

The transition to space is a fluent one without clear borders,

向太空的过渡是平缓的，并没有明确的边界，

but humans decided that space starts here. 表達脈絡

但人类规定太空从这里开始。

At about 100 km,

在100公里左右，

Earth stops and space begins, 習語

地球的领域结束，太空开始，

though the atmosphere extends a bit further.

尽管大气层还会延伸得稍微远一点。

In this region,

在这个区域，

we find the ionosphere, the aurora borealis, and the ISS.

我们可以找到电离层、北极光和国际空间站（ISS）。

And the outermost layer is the exosphere,

最外层是散逸层，

stretching up to 10,000 km. It merges fluently with outer space,

向上延伸可达10000公里。它与外太空平滑融合，

where there's no atmosphere at all.

在最外围没有任何大气层。

The atoms and molecules in this area are so far apart 語法

这一区域的原子和分子相距极其遥远，

that they can travel hundreds of kilometers

以至于它们可以穿行数百公里，

without colliding with each other.

都不会相互碰撞。

Okay.

好吧。

Humans in their present form have only been around for 200,000 years. 語法

现代形态的人类存在了不过20万年。

That's 0.004% of Earth's history.

这只占地球历史的0.004%。

Not long really. 表達脈絡

其实并不算长。

And here we are now,

而现在我们就在这里，

living in a thin moist layer on a small wet rock. 習語

生活在一个潮湿小岩石上的湿润薄层中。

We call this rock Earth.

我们把这块岩石称为地球。

It is the product of the universe's deepest workings, 表達脈絡

它是宇宙最深层次运转的产物，

the result of a constant process of creation and destruction

是宇宙各处始终在发生的

happening all over the universe all the time,

创造与毁灭不断交替的过程的结果，

helped by chance, the laws of the universe, and random events.

并借由机缘巧合、宇宙法则与随机事件的共同作用而成。

We are really lucky.

我们真的很幸运。