關於地球你需要知道的一切：英語精讀講義

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

地球是宇宙中已知的每一個生命形式的家園。

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

它的年齡大約是宇宙年齡的三分之一，

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

而且承認吧，它真的很美。

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

它是一個略微扁平的球體，擁有重金屬核心和較輕的表面地殼，

wrapped in a thin sliver of sweet air to breathe 講解

被薄薄一層供呼吸的甜美空氣包裹著，

with vast oceans, fertile plains, magnificent mountains,

有著浩瀚的海洋、肥沃的平原、雄偉的山脈、

fresh water rivers, streams, lakes and aquifers

淡水河、溪流、湖泊和蓄水層，

orbiting a star which warms us and gives us energy.

圍繞著一顆為我們提供溫暖和能量的恆星運行。

But how did our home come into existence 片語搭配

但是，我們的家園是如何誕生的？

and what's it made of? 片語搭配

它又是怎樣構成的？

4.6 billion years ago,

46億年前，

Earth was created from the remnants of dead stars 用詞

地球由死亡恆星的殘骸孕育而成，

that collected in a giant dirty gas cloud.

這些殘骸聚集在一團巨大的塵埃氣體雲中。

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

氣體雲的中心變得越來越緻密，並形成了一個吸積盤。

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

細小的顆粒開始聚集成團，形成越來越大的物體，

until they formed the objects we call planets today.

直到它們形成了今天我們稱之為行星的天體。

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

這個過程耗時1000萬到2000萬年，且至今尚未被完全弄明白。

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

大概就在這個太陽系還處於年輕且混亂的時期，

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

一個約有火星那麼大的巨大天體撞擊了我們的家園。

The impact was violent

撞擊非常猛烈，

and if the object had been more massive, 文法

如果那個天體再大一點，

it might have destroyed Earth.

它可能就把地球給毀滅了。

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

地球的物質被撞飛到軌道上，形成了月球，

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

相對於它所環繞的行星而言，它是太陽系中最大的衛星。

At this time, Earth was a hot hell,

那時的地球如同一個熾熱的地獄，

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

不斷遭到小行星的撞擊，到處是岩漿的海洋和有毒的大氣。

But something was about to change drastically. 文法

但有些事情即將發生劇變。

Earth cooled down.

地球冷卻了下來。

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

地球內部的水向地表游移，並以降雨的形式落到地球上，

only to vaporize again and become clouds. 文法

接著再次蒸發成為雲層。

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

數以百萬計的小行星為我們的星球帶來了越來越多的水。

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

地球上所有的水加起來，與地球相比大約是這個體積。

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

今天，地球表面71%是水，29%是陸地。

97.5% is saline water,

97.5%是鹹水，

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. 片語動詞

僅有約1%構成了剩餘的地下水。

But even this small part is mostly frozen.

但這極小的一部分水大部分也是冰凍的。

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

實際上，我們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.

更小的一部分存在於生物體內。

So, gradually the Earth cooled down

於是，地球逐漸冷卻下來，

and the surface formed a thin crust.

表面形成了一層薄薄的地殼。

But inside the Earth,

但在地球內部，

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

熾熱的岩石不斷翻滾，從下方推動地殼並使其斷裂。

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

這個過程被稱為板塊構造，而且此刻正在發生。

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

將來我們會專門做一整期影片來講解它。

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

現在，我們只需知道地球的地殼

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

是由四處移動的獨立巨大板塊組成的。

As they meet, they crumble and create mighty mountains

當它們相遇時，會相互擠壓並隆起雄偉的山脈，

or violently plunge back down deeper into Earth,

或者劇烈地重新沉入地球深處，

creating deep trenches.

形成深邃的海溝。

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

地球上的最高點就是這樣形成的，

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

即聖母峰，還有最深處的馬里亞納海溝。

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

從我們的視角來看，地球上的高山和海溝的確雄偉，

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

但當你觀看地球的剖面圖時，

you can see how tiny they actually are.

你就會發現它們實際有多麼微不足道。

The part we stand on is the crust,

我們所站立的部分是地殼，

which is about 50 km thick,

它的厚度約為50公里，

though it can vary between 5 and 70 km.

不過它可以在5到70公里之間變化。

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

順帶一提，人類鑽出最深的洞深達12.262公里。

After the crust comes the mantle. 文法

地殼之下是地函。

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

它是一層矽酸鹽岩石殼，厚約2900公里。

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

地函由上地函和下地函組成。

The upper mantle has different regions too.

上地函也有不同的區域劃分。

Its upper part,

它的上部，

which is viscous and carries the crust,

也就是具有黏性並承載著地殼的部分，

is called the lithosphere.

被稱為岩石圈。

After that, there comes the asthenosphere,

在它下面的是軟流圈，

which consists of less mobile, mostly solid material.

主要由流動性較低、大體呈固態的物質構成。

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

下地函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

地球的外地核是一層液態的鐵和鎳，

about 2,266 km thick.

厚約2266公里。

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

溫度從4000°C到5700°C不等。

And in the center is the inner core.

在中心的是內地核。

It's mostly solid,

它主要是固態的，

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

是一個由鐵鎳合金構成的球體，半徑約為1200公里，

70% of the size of the Moon,

大小相當於月球的70%，

and about the temperature of the surface of the Sun.

溫度與太陽表面差不多。

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

它正在以每年約1公厘的估計速度緩慢增長。

Now, for some perspective. 表達脈絡

現在，讓我們換個角度看看。

This small layer of crust

這一小薄層的地殼，

crystallized melt products of former molten mantle

即曾經熔融的地函所結晶出的熔體產物，

is where we live.

就是我們居住的地方。

Then, there's Earth's magnetic field.

接下來是地球的磁場。

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

這是一種無形的現象，能偏轉來自太陽和其他高能粒子流，

allowing for a stable environment 片語動詞

從而提供一個穩定的環境，

with comparatively little radiation impact on Earth.

讓地球受到輻射的影響相對較小。

But why is it there?

但它為什麼會存在呢？

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

事實上，關於這一點我們並不十分清楚。

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

我們知道它與地球的核心有關。

Inside this metal sphere,

在這個金屬球體內部，

large electrical currents flow in complicated patterns.

巨大的電流以複雜的模式流動。

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

它們根據電動力學定律，

according to the laws of electrodynamics.

產生了一個能夠自我穩定的磁場。

This entire system is called the dynamo.

整個系統被稱為發電機效應。

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

但別被我們騙了，別以為我們已完全弄懂了這一切。

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

說到令人驚嘆的資訊，那環繞著我們的空氣又如何呢？

By volume, dry air consists mostly of nitrogen, 用詞

按體積計算，乾燥的空氣主要由氮氣、

oxygen, argon, carbon,

氧氣、氬氣、碳、

a variable amount of water vapor, 片語搭配

數量不等的水蒸氣，

and small amounts of other gases.

以及少量其他氣體組成。

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

人類非常依賴大氣層的最底層，

the troposphere, where the weather is.

即對流層，也就是產生天氣的地方。

It's 12 km thick on average. 片語搭配

它的平均厚度為12公里。

Above that is the stratosphere, 文法

之上是平流層，

which is where the ozone layer protects

那是臭氧層所在之處，它保護著

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

我們免受太陽最強烈光線的傷害。

Above that is the mesosphere,

再往上是中氣層，

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

它是地球上最冷的地方，平均溫度約為-85°C。

At about 80 km up, the thermosphere starts.

在80公里左右的高空，熱層開始出現。

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

向太空的過渡是平緩的，並沒有明確的邊界，

but humans decided that space starts here. 表達脈絡

但人類規定太空從這裡開始。

At about 100 km,

在100公里左右，

Earth stops and space begins, 慣用語

地球的領域結束，太空開始，

though the atmosphere extends a bit further.

儘管大氣層還會延伸得稍微遠一點。

In this region,

在這個區域，

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

我們可以找到電離層、北極光和國際太空站（ISS）。

And the outermost layer is the exosphere,

最外層是散逸層，

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

向上延伸可達10000公里。它與外太空平滑融合，

where there's no atmosphere at all.

在最外圍沒有任何大氣層。

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

這一區域的原子和分子相距極其遙遠，

that they can travel hundreds of kilometers

以至於它們可以穿行數百公里，

without colliding with each other.

都不會相互碰撞。

Okay.

好吧。

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

現代形態的人類存在了不過20萬年。

That's 0.004% of Earth's history.

這只占地球歷史的0.004%。

Not long really. 表達脈絡

其實並不算長。

And here we are now,

而現在我們就在這裡，

living in a thin moist layer on a small wet rock. 慣用語

生活在一個潮濕小岩石上的濕潤薄層中。

We call this rock Earth.

我們把這塊岩石稱為地球。

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

它是宇宙最深層次運轉的產物，

the result of a constant process of creation and destruction

是宇宙各處始終在發生的

happening all over the universe all the time,

創造與毀滅不斷交替的過程的結果，

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

並藉由機緣巧合、宇宙法則與隨機事件的共同作用而成。

We are really lucky.

我們真的很幸運。