And a lunar eclipse is the opposite -- when the Earth’s shadow falls on the moon

月食則恰恰相反，是當地球的影子落在月球上

The two sections of the shadow, the dark umbra and the partially shaded penumbra,

陰影分為二部份，太陽光線全部及部份被地球阻擋造成的本影區和半影區

their placement determines which type of eclipse we can see from Earth.

陰影的位置決定了我們可以從地球上看到哪種類型的月食

But not all eclipses are made equal.

但不是每次日、月食都是相同的

The most spectacular, the one for your bucket list is a total eclipse of the sun.

最壯觀的、值得你放進人生清單的就是日全食

A total solar eclipse begins as a partial eclipse.

日全食開始於日偏食

You’ll notice trees projecting the crescent sun,

你會看到被新月型的太陽投射出的樹影

and shadows becoming sharper than normal.

比平常更加清晰

The landscape darkens to a bluish-grey and you’ll start to feel the temperature drop.

景觀變成灰藍色，你會開始感覺到溫度下降

From the west, the moon’s shadow rushes toward you like a silent storm.

從西邊看，月亮的影子像無聲的風暴般衝向你

Look up and you’ll see the last sliver of the sun sparkling like a diamond ring,

抬頭看，你會看到最後一縷陽光就像鑽石戒指一樣閃閃發光

before it’s broken into a string of beads by the moon’s rough terrain.

然後被月球粗造的表面打碎成一串珠子

Now you can see the pearly glow of the sun’s corona and the pink and red light from the hydrogen

現在，你可以看到太陽日冕的白色光芒

gas of the chromosphere.

和氫氣造成的粉色和紅色光芒

Together these make up the sun’s outer atmosphere, and a total solar eclipse is the only occasion

這些東西一起構成了太陽的外部大氣層，而日全食是你

you have to lay eyes on it.

唯一可以看到這個景象的時候

This is totality and if you get a chance to see it, you should.

這就是全食，如果有機會，你應該去看

The moon orbits earth every 29.5 days, but we don’t get eclipses every month.

月球每 29.5 天繞地球運行一次，但是不會每個月都發生日食或月食

That’s because the moon’s orbit is not in line with earth’s orbit.

那是因為月球的軌道與地球軌道不一致

it’s tilted about 5 degrees.

月球的軌道倾斜了大约 5 度

That doesn’t seem like much but keep in mind that the scale of the model we’re showing

這看起來並不多，但請記住，我們展示的模型

to you is way off.

遠小於實際的規模

If the Earth and moon are this size, the distance between them should be around 10 ft.

如果地球和月球是這樣的大小，它們之間的距離應該在 10 英尺左右

At this distance, 5 degrees is enough to keep the moon’s shadow off of Earth and the Earth’s

在這個距離上，5 度足以在大部份的時候使月球的影子照不到地球，

shadow off the moon most months.

地球的影子也照不到月球

So why do we ever get eclipses?

那什麼時候月食才會發生？

Because there are two points where the moon’s orbit crosses the sun’s plane, called nodes.

因為月球的軌道有兩個點與太陽運行的平面相交，稱為節點

And as the Earth moves along its annual orbit, those points line up with the sun about twice a year.

而當地球沿著自己的軌道運行，這些節點與太陽每年約交會兩次

As the moon passes between the sun and Earth at that time, we get a solar eclipse.

當月球運行在交會點的時候剛好在太陽和地球之間，就會發生日食

When it’s behind Earth at that time, we get a lunar eclipse.

而當它運行到地球背面時，就會發生月食

There are a ton of orbital quirks that make predicting eclipses really complicated, but

有很多不同種的說法，讓預測月蝕變得很複雜

in general we’ll have a few solar and a few lunar eclipses

但總的來說，我們每年都會看到幾次

of some sort every year.

日食和月食

But you’re more likely to see a total lunar eclipse in your lifetime than a total solar one.

但相較於日全食而言，在你的一生中，你更有機會看到月全食

The totality of a lunar eclipse can last well over an hour and it’s viewable for anyone

月全食從開始到結束可持續一個多小時，而且任何身處在地球黑夜半邊的人

on the night side of earth.

都可以看見月全食

The moon often turns red during a total lunar eclipse because our planet’s atmosphere

在月全食期間月球通常會變成紅色，因為地球的大氣層會將

scatters the shorter bluer wavelengths of light, while the longer, redder wavelengths

太陽波長較短的藍色光散射掉，而波長較長的紅色光

pass through.

則會通過而射到月球上

Or to put it another way, a total lunar eclipse projects all of the world’s sunsets and

或者可以這麼說，月全食將全世界所有的日出和日落

sunrises onto the moon.

都映射到月球上

Total solar eclipses seem much more rare because totality lasts just a few minutes, and although

日全食似乎更為罕見，因為總體持續時間只有幾分鐘

Earth gets a total solar eclipse every 18 months on average, each one is only viewable

雖然地球上平均每 18 個月會有一次日全食

by less than half a percent of Earth’s surface.

但只有在少於地球表面積 0.5% 的地方可以有機會看到

Eclipse chasers travel all over the world to put themselves in the path of the shadow.

日、月食追逐者為了要能在陰影地帶，會跑遍全世界

In a total solar eclipse, the moon precisely covers the sun from the vantage point of some

日全食的發生，是從地球上某個點的有利位置看過去

place on Earth.

月亮剛好精準地覆蓋住整個太陽

This is possible because by coincidence, the sun and the moon appear to be about the same

這是可能的，因為巧合的是，太陽和月亮在我們的天空中

size in our sky.

看起來剛好一樣大

While the sun is 400 times bigger than the moon, it’s also about 400 times farther away.

雖然太陽比月球大 400 倍，但太陽到地球的距離也差不多是月球的 400 倍，所以看起來會一樣大

But this alignment isn’t constant.

但是地球、月亮、太陽成一直線並不是恆定的

the moon has an elliptical orbit.

月亮有一個橢圓形的軌道

Its size varies about 12% throughout a month.

軌道的大小在一個月內約會有 12% 的變化

When it’s closer to us, we can get total solar eclipses, but less than 30% of solar

當月亮比較靠近地球時，就可以看到日全食

eclipses are total.

但是機率不到 30%

More often, we get partial eclipses, where the alignment is a bit off, or annular eclipses,

更常看到的是日偏食，也就是地球、月亮、太陽不在一直線的時候，或者是日環食

where the moon is too far away to fully block the sun, leaving a ring of sunlight around

就是月球遠距地球太遠而無法完全遮住太陽，而在月球周圍

the moon.

產生一圈陽光

In the far future, earth will only get annular and partial solar eclipses because our moon

在很久的將來，地球上只能看到日偏食或日環食

is moving further away.

因為月球正在逐漸遠離地球

We know that because Buzz Aldrin and Neil Armstrong left mirrors on the moon in 1969.

我們會知道，是因為 1969 年美國太空人尼爾. 阿姆斯壯和巴茲. 艾德林在月球上放置了幾面鏡子

Astronomers bounce lasers off those mirrors to measure the moon’s distance.

天文學家會對這些鏡子發射雷射光，並從這些鏡子反射的雷射光來測量月球的距離

And that’s how they found out that the moon is moving away from Earth by more than 3 cm

這就是他們如何發現月球正在以每年 3 公分的速率

per year.

遠離地球

So in a billion years or so, whatever creatures live here will witness Earth’s very last

因此再過十億年左右，生活在這裡的所有生物都將見證地球上最後一次的

total solar eclipse.

日全食

“We can see on the Radio One screen, a fantastic total solar eclipse taken from the pictures

「我們在 Radio One 螢幕上可以看到，從雲層上方的景象中捕捉到

above the clouds.”

一個美妙的日全食畫面。」

" This is just fantastic.”

「真是太壯觀了。」

A lot of early civilizations feared eclipses.

許多古老的文明害怕日、月食的發生

They were often seen as an attack on the sun or moon by the forces of darkness.

他們把這種現象視為是來自黑暗勢力的攻擊

But now that we understand our place in space, eclipses are an occasion for awe,

但是現在我們明白了地球在宇宙中的位置，日、月食的發生是一個我們對造物者

and for gratitude.

敬畏和感恩的時刻

All over the galaxy rocks are casting shadows on other rocks.

整個銀河系的星球都在其他星球上投射出陰影

But only here, as far as we know, is there someone to notice them.

但就我們所知，只有在這裡 (地球) 的人注意到這個現象的存在