What creates a total solar eclipse? - Andy Cohen

話說日全食—安迪·柯漢 (Andy Cohen)

譯者: Regina Chu 審譯者: 瑞文Eleven 林Lim

On August 21, 2017

2017 年 8 月 21 日

the shadow of the Moon will pass

月亮的陰影會橫掃美國

from the west coast to the east coast of the U.S.

從西岸到東岸

Our blue sky will turn black as night

我們的藍天會變得像晚上一樣黑

還會有滿天星斗

and fill with stars,

and there will be a hole in the sky

同時天空中也會出現一個洞

where the Sun used to be,

就是太陽之前的位置

surrounded by the fiery ring of the Sun's corona,

會被日冕形成的火環所圍繞

a total eclipse of the Sun.

這就是日全食

This will truly be a historic event.

這將會是一個歷史性事件

Accounts of solar eclipses

關於日食的紀錄

date way back on the written record.

可以追溯回古時史書

The early Mesopotamians wrote

早期的美索不達米亞人寫道：

that the Sun was put to shame

太陽蒙羞了

during the solar eclipse of the 14th century B.C.E.

西元前第十四世紀的一場日食

and it may have started

可能是導致

the Sun worship of the Egyptian pharaoh Akhenaten.

埃及法老阿肯那頓太陽膜拜的開端

Ancient Chinese astrologers paid with their lives

古代的中國占星術士如果漏報了日食

if they failed to predict the solar eclipse

或無法預示皇帝的命兆

and portend the fate of their emperors

是要賠上性命的

因為太陽就是皇帝的象徵

whose symbol was the Sun.

The earliest date of a specific event in human history,

人類史上最早記載日期的特定事件

為利底亞與米底亞之間的戰爭

a battle between the armies of Lydia and Media,

occurred on May 28, 535 B.C.E.

發生於西元前 535 年 5 月 28 日

when a solar eclipse caused the soldiers

當時發生的日食造成

to lay down their arms and declare a truce.

士兵棄械並宣告停戰

So how does it happen?

那日食是怎麼形成的？

During a total solar eclipse,

當日全食發生時

the Moon moves between the Earth and the Sun.

月球運行到地球與太陽之間

When this happens, the disc of the Moon

而且月球的盤面

appears to perfectly cover the disc of the Sun

看起來完全擋住太陽

even though the Sun is much larger than the Moon.

即使太陽比月球大很多

But how is this possible?

但這怎麼可能？

The Sun is 400 times bigger than the Moon,

太陽比月球大了 400 倍

but by sheer coincidence,

但是就有這麼巧

the Moon is 390 times closer to Earth.

月球到地球的距離 比日地距離近 390 倍

Size and distance cancel each other out

尺寸及距離的效應互相抵銷

so that the Moon and Sun appear

因此月球與太陽看起來

to be almost the exactly same size.

大小幾乎相同

Every time the Moon orbits the Earth,

每次月球繞地球公轉

once every 27.3 days,

一圈 27.3 天

it has to pass between the Earth and the Sun,

它總會穿過地球與太陽之間一次

a stage called the new moon phase.

這時期稱做新月(朔)

And every time it passes,

每次它穿過

the New Moon has a chance to block out the Sun.

新月就有機會擋住太陽

Most of the time,

大部分的時間

the Moon passes a little above

月球穿過的位置

or a little below the Sun,

可能比太陽高一點或低一點

but if they align perfectly,

但如果它們完全對齊

the shadow of the Moon

月球的陰影

will make a narrow path across Earth

就會在地球上掃出一條狹長的食帶

and those in the shadows will see a total solar eclipse.

只有在食帶中的人才能看到日全食

Just like on night side of the Earth,

就像地球在夜晚那側一般

the sky during a total eclipse is black

天空在日全食期間是黑暗的

and filled with stars.

並可見滿天星斗

But while the moon perfectly covers

但是就算月球完全遮蓋

the surface of the Sun,

太陽的表面

it doesn't block out the Sun's outer atmosphere,

它也擋不住太陽的大氣層

its corona, which appears as a fiery ring

即日冕，看起來就像一圈火環

around the dark disc of the moon.

在月球暗影的外圍

Solar eclipses occur several times a year,

一年會發生好幾次日食

but most often they are partial eclipses

但多數情況是日偏食

where the Moon doesn't quite line up with the Sun.

也就是月球與太陽並非完全對齊

And, when the Moon and Sun are perfectly aligned,

再者，有時月球與太陽排成一直線時

the Moon is usually too far from Earth in its orbit

月球在公轉軌道上的位置 離地球太遠

to completely cover the Sun,

無法完全遮蓋太陽

creating an annular eclipse.

就會發生日環食

During an annular or partial eclipse,

在日環食或日偏食發生時

the sky remains bright.

天空依然明亮

Even on those rare occasions of a total eclipse,

即使是很罕見的日全食

the Moon's shadow is most likely to fall

月球的陰影最有可能落在

on the 70% of Earth that is covered by water,

佔地球 70% 的海面上

and few people, if any, will see it.

所以只有極少數人有幸能見到此奇景

The eclipse of 2017 will be remarkable on a larger scale

2017 年的日食很值得注意， 因為長久來看

because the Moon is slowly moving away from Earth.

月球正逐漸遠離地球

If a furry ancestor of ours had bothered to look up

如果我們有著毛皮的祖先願意費神

during a solar eclipse a hundred million years ago,

在幾億年前的一場日食中抬頭仰望

it wouldn't have seen the fiery corona of the Sun.

他不會看到太陽的日冕火環

It would have just been dark.

只有一片漆黑

Eventually, the Moon will have moved too far from Earth

總有一天，月球會因離地球太遠

to completely cover the disc of the Sun.

再也無法完全遮蔽太陽

It is only during our little wink of Earth's history

只有在地球歷史上這段 轉瞬般短暫的時間內

that the Moon is at just the right distance

月球位在恰好的距離

to cause a total solar eclipse

能造成日全食

yet not block the Sun's corona.

卻不會擋住日冕

So on August 21, 2017,

所以在 2017 年 8 月 21 日

when the Moon exactly lines up with the Sun

當月球與太陽恰恰形成一直線

and the Moon is close enough to the Earth,

而且月球與地球的距離夠近

its shadow will cross the U.S.

它的暗影才會橫掃美國

and, if you happen to be in its narrow path,

如果你剛好位在月影的狹長食帶上

you will witness one of the most

你將會見證一場

awe-inspiring sights in the universe.

宇宙間最令人敬畏的景象

But, as incredible as this event will be,

但是，就像這起事件非常奇妙

total eclipses are one of the most dangerous as well.

日全食也非常危險

Only specially tinted filters,

只有專為觀察太陽而設計的

specifically designed to observe the Sun,

特殊染色濾鏡

should be used.

能拿來看日食

The eclipse might put the Sun to shame,

日食可能使太陽蒙羞了

but even a shamed Sun

但是即使是蒙羞的太陽

can seriously damage your eyes.

也能嚴重傷害你的眼睛