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  • It has no taste, color or smell, and we often look right through it.

    它沒有味道、顏色、或氣味 而且我們經常看透過它,

  • It covers over 70% of the Earth,

    它覆蓋了 70% 以上的地球

  • cycling from the oceans and rivers to the clouds and back again.

    從海洋、河流進入到雲氣裡 又降回到地面一再重複此循環

  • It even makes up about 60% of our bodies.

    甚至我們人體的 60% 也是水分

  • With all this water around and inside us,

    在我們的週遭和體內有著這麼多水分

  • it's easy to take its presence for granted.

    就很容易把它的存在不當成是一回事

  • But in the rest of the solar system, liquid water is almost impossible to find.

    但是在太陽系的其他地方 幾乎找不到液態水

  • So how did our planet end up with so much of this substance

    我們的星球為什麼 會有著這麼多液態水

  • and where did it come from?

    它又到底是從哪裡來到地球的呢

  • As you probably know,

    就像你或許知道的一樣

  • a water molecule consists of two basic parts.

    水的分子是由兩個基本成分組成

  • Hydrogen, the simplest of all elements,

    氫氣 ─ 這最普通的元素

  • has been around since close to the beginning of our universe.

    大概從我們的宇宙誕生之初 至今就一直存在著

  • Oxygen entered the scene several hundred million years later

    氧氣在星球開始形成 的數億年後也進場來了

  • after stars began to form.

    在這些赤紅火海中心 的巨大壓力是如此之龐大

  • The massive pressure at the center of these fiery infernos was so great

    氫原子熔合在一起構成了氦

  • that hydrogen atoms fused together to form helium.

    氦接下來又熔合成了重元素

  • Helium, in turn, fused to form heavier elements,

    在稱為「核合成」的過程裡 熔合成像是鈹、碳、或是氧氣

  • like beryllium, carbon and oxygen in a process known as nucleosynthesis.

    當星球終究瓦解和爆炸成了超新星

  • When stars eventually collapsed and exploded into supernovas,

    這些新元素就散佈到整個宇宙當中

  • these new elements were spread across the universe

    接著結合成新的聚合物, 像是我們今天所熟悉的水 (H2O)

  • and combined into new compounds, like the now familiar H2O.

    這些水分子存在於混濁的雲體當中

  • These water molecules were present in the dusty cloud

    那些雲體又形成了我們的太陽系

  • that formed our solar system

    在太陽系形成後 更多水分撞擊到了地球

  • and more collided with our planet after its formation.

    這邊有個目前找不到答案的大疑問

  • But there's a big question that we don't have the answer to:

    有多少水分來到了地球? 以及什麼時候來的?

  • how much water arrived on Earth, and when?

    假使像某個理論所說的一樣

  • If, as one theory goes,

    當地球岩體形成時只有 相對少量的水在地球上

  • relatively small amounts of water were present on Earth when the rock formed,

    高溫以及缺少氣體籠罩住地球

  • the high temperatures and lack of any surrounding atmosphere

    會造成水分蒸發而回到太空裡

  • would have caused it to evaporate back into space.

    水分沒有辦法留在這星球上

  • Water would have been unable to remain on the planet

    直到幾億年之後

  • until hundreds of millions of years later

    當我們最早的大氣層經由 「氣體釋出」的過程所形成

  • when our first atmosphere formed through a process called outgassing.

    這發生在當地心裡的熔化岩石

  • This occurred when molten rock in the Earth's core

    釋放出火山氣體到地表

  • released volcanic gasses to the surface,

    創造出一層外覆 然後就可以鎖住外逸的水分

  • creating a layer that could then trap escaping water.

    那麼水分後來是如何回到星球上呢?

  • So how then did water get back to the planet?

    科學人員長久以來猜測

  • Scientists have long suspected

    許多的水分是被冰晶彗星帶來的

  • that much of it was brought by ice-bearing comets,

    或更可能是在數百萬年前 小行星群轟炸地球時所帶來的

  • or more likely asteroids that bombarded the Earth over millions of years.

    最新的研究對這個理論提出了質疑

  • Recent research has challenged this theory.

    在檢測隕石化石的時候

  • In examining carbonaceous chondrite meterorites

    該隕石是在太陽系誕生不久後形成的

  • that formed shorty after the birth of our solar system,

    科學人員發現到它們不只含帶水分

  • scientists have found that not only did they contain water,

    而且礦物化學成分與地球的岩石、

  • but their mineral chemical composition matched rocks on Earth

    以及與地球同時間形成的 小行星之樣本吻合

  • and samples from an asteroid that formed at the same time as our planet.

    這代表地球可能早在水分能留住前 就積存了大量的水分

  • This suggests that the Earth may have accumulated

    儘管是缺少了大氣層

  • a substantial amount of water early on that was able to stay put,

    儘管小行星可能在遠古也帶來了很多水

  • despite the lack of an atmosphere,

    假若這個成為了事實

  • though asteroids may have brought more over the eons.

    生命體可能出現於 比我們以前所知道的還要更早

  • If this turns out to be true,

    所以我們尚未確切地知道 到底地球的水分

  • life may have formed much earlier than previously thought.

    是來自於它最初形成的時候

  • So we do not yet definitively know whether the water on Earth

    或是之後的影響所造成

  • came from its initial formation,

    抑或夾雜著這兩者的理由

  • later impacts,

    不管如何,從我們的蓮蓬頭、 自來水管和水龍頭跑出來的水

  • or some combination of the two.

    就不單純是從附近的湖泊 或河流所來的東西

  • Regardless, the water that runs from our showers, drinking fountains and faucets

    而是先歷經了一段跟宇宙有關的 不平靜旅程來到了地球

  • is something that didn't just come from a nearby lake or river,

  • but first underwent a cosmic and chaotic journey to get here.

It has no taste, color or smell, and we often look right through it.

它沒有味道、顏色、或氣味 而且我們經常看透過它,

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影片操作 你可以在這邊進行「影片」的調整,以及「字幕」的顯示

B1 中級 中文 美國腔 TED-Ed 水分 地球 形成 太陽系 星球

【TED-Ed】地球上的水從哪裡來?- Zachary Metz (【TED-Ed】Where did Earth’s water come from? - Zachary Metz)

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    稲葉白兎 發佈於 2021 年 01 月 14 日
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