如果你沒看過美國自由女神像的老照片，你大概以為自由女神像一直都是綠色的吧。其實，最初的女神像是古銅色的，那她是怎么一步一步變成綠色的呢?一起來了解其中奧妙。

New York's iconic, blue-green statue of liberty wasn't always green.
紐約的標志性藍綠色自由女神像并不一直都是綠色的。
When the statue was gifted to the US from France in 1885, she was actually a shiny copper color.
1885年法國把這座女神像送給美國時，她實際上是亮閃閃的古銅色。
A new video reveals the chemical reactions involving oxygen and even air pollution that led to her color change from copper to liberty green.
最近有個視頻揭示了氧氣和空氣污染是如何與女神像發生化學反應，把古銅色變成綠色的。
The statue of liberty was a gift from France to the US as a way of commemorating the US's fight for independence, as well as their own aspiration for democracy.
法國將這座自由女神像送給美國作為禮物，是為了紀念美國的獨立戰爭，以及法國自己對民主的渴望。
A video, published by the American Chemical Society, explains that the 305-foot (93 meter) statue was built over nine years in sections of copper skin on top of an iron skeleton.
由美國化學學會發布的這個視頻解釋了這座花費九年造成的高達305英尺(93米)的雕像是如何在鐵質框架上包上一層銅。
According to the National Park Service, the statue is made of thirty tons of copper - enough to make 435 million pennies.
美國國家公園管理局稱，自由女神像由30噸銅打造而成，這些銅足以制造4.35億枚美分硬幣。

'In her first few decades in the Big Apple, the statue slowly turned from that shiny copper color to a dull brown and the, finally, to the blue-green, or as they'd say back in France, 'verdigris' we see today,' said the video's narrator.
該視頻的解說員說：“在自由女神像入駐紐約市的頭幾十年，女神像慢慢地從閃亮的古銅色變成了暗淡的棕色，最后變成了我們今天看到的藍綠色，或者法國人所謂的‘銅綠色’。”
When it changed color, some officials suggested restoring her back to her original color, but after the public protested against this decision, she was left the way she is.
自由女神像最初變色時，一些官員建議將其還原成最初的顏色，但是公眾對這個決定表示抗議，于是女神像的這個顏色就保留了下來。
The statue's color change was as a result of oxidation reactions between copper and the air.
自由女神像變色是銅和空氣氧化反應的結果。
But it was more than one reaction - the color change is due to about 30 years worth of different reactions leading to a mixture of greenish minerals.
但是這種變色不只緣于一種化學反應，而是三十年間多種不同的化學反應相混合才導致了這種綠色。
Oxidation reactions happen when an atom loses an electron to another atom.
當一個原子的一個電子轉移給了另一個原子，這時就發生了氧化反應。
In the case of the statue of liberty, her color change was bound to happen due to oxygen in the atmosphere that is 'hungry' for electrons.
自由女神像的顏色變化是必然會發生的，因為周圍空氣中的氧氣“渴求”電子。
On top of this, elements of New York City's polluted air added to the color change too.
除此以外，紐約市空氣中的污染物質也促成了顏色的變化。
 
The first chemical reaction of the color change involved copper giving up electrons to electron-hungry oxygen in the atmosphere.
和顏色變化有關的第一個化學反應是銅將電子轉移給了周圍渴求電子的氧氣。
This led to a mineral called cuprite - which is pinkish red.
這種化學反應的結果是生成一種叫作赤銅礦的礦物質，赤銅礦呈肉紅色。
Then, cuprite loses even more electrons to oxygen, forming a new mineral called tenorite, which is blackish in color.
赤銅礦失掉更多電子給氧氣，從而形成了名為黑銅礦的新礦物質，黑銅礦顏色發黑。
The black color of tenorite explains why the statue got darker over time, forming a dark brown color.
黑銅礦的黑色解釋了為什么女神像這些年來顏色越來越暗，呈現出深棕色。
Then, further chemical reactions occurred when sulfur in the atmosphere reacts with water.
接下來，當周圍空氣中的硫與水接觸時，又發生了進一步的化學反應。
Sulfur comes from natural processes such as volcanic eruptions, but also from man-made emissions from boats, cars, airplanes and factories.
硫來自火山噴發等自然過程，但船舶、汽車、飛機和工廠的人為排放也會產生硫。
When sulfur dioxide in the atmosphere reacts with water, it produces sulfuric acid.
當空氣中的二氧化硫與水發生反應時，就會產生硫酸。
Sulfuric acid forms green minerals with copper oxides, so the sulfuric acid in the atmosphere made the state green over time.
硫酸和氧化銅發生反應，生成了綠色的礦物質，就這樣，隨著時間的流逝，周圍空氣中的硫酸將自由女神像變成了綠色。
Added to that, chloride from the sea spray surrounding Ellis Island where the statue is located made the statue even greener.
此外，自由女神像所在的埃利斯島四周海浪中的氯化物讓女神像的顏色變得更綠。
The statue stayed this way for over 100 years because the exposed copper is now oxidized and stable, but the statue wouldn't be the same anywhere else.
自由女神像就這樣保持了100多年，因為暴露在空氣中的銅已經被氧化，化學性質穩定下來，但這尊女神像如果放在其他任何地方都不會是這個顏色。