The footage was filmed in Sweden over Christmas 2013, which got us thinking about the Aurora Borealis.

這段畫面在 2013 年的聖誕節時攝於瑞典，讓人不禁想要揭開北極光的神秘面紗。

Here are five remarkable facts you should know!

以下是你不可不知五件關於北極光的小知識！

I'm Sophie, and welcome to the Countdown.

我是 Sophie，歡迎來到「倒數計時」。

What causes an aurora?

是什麼形成了極光？

Well, the Earth is surrounded by a magnetic field, which normally helps deflect harmful radiation.

地球四周環繞著磁場，因此能夠使有害的輻射光轉向。

When charged particles from the sun, known as the solar wind, fly towards our planet, the field speeds up those particles and directs them towards the magnetic north and south poles.

當太陽中帶電的粒子，一般稱為太陽風，飛向地球時，磁場會加速這些粒子，並將他們導向磁北極和磁南極。

As the solar wind hits our atmosphere, the charged particles collide with atmospheric atoms and molecules, and transfer their energy.

在太陽風接觸到大氣候，帶電粒子和大氣中的原子及分子撞擊，並轉換成能量。

These gas molecules then spit that energy back out in the form of light.

這些氣體分子接著將能量轉換成光的形式釋放出來。

Our atmosphere is mostly made up of oxygen and nitrogen, which produce a variety of colors.

我們的大氣主要是由氧氣和氮氣所構成，而它們會產生各種不同的顏色。

Atoms of nitrogen release blue light, while two nitrogen atoms bonded together give off a purple hue; the color also depends on altitude.

氮原子會釋放出藍光，但當兩個氮原子結合時，則會釋出紫光；顏色也會因為高度而有所不同。

Oxygen releases green light above 100km, but switches to a reddish color above 240km.

氧氣在海拔 100 公里會釋出綠光，但升高至海拔 240 公里時，會轉變成紅紅的光。

And when colors combine, they can produce other shades, like pink and yellow.

而且當顏色融合在一起，就會產生其他像是粉紅色和黃色等的顏色。

The aurora can be a single hue, or a shimmering rainbow.

極光可以是單一的顏色，也可以是閃閃發光的彩虹。

Unfortunately, the solar activity that gives us auroras also has some unwanted effects.

然而，太陽的活動所造成的極光也會帶來一些負面的影響。

On the planet's surface, charged solar particles can interfere with satellite communication, along with radio, television and telephone signals.

在地球的表面，帶電粒子會干擾衛星的訊號連結，還有廣播、電視和電話的訊號。

Navigation instruments like compasses become unreliable.

像是指南針等的導航器具也會變得不靈光。

The solar weather can even cause electrical surges, that interrupt the power grid and sometimes result in power outages.

太陽活動甚至會造成電力劇增，並可能干擾電力網路，造成電力超載。

Auroras have fascinated humans for thousands of years.

極光讓人類著迷了好幾千年。

This cave painting, which dates back to 30,000 BC, may represent the earliest observation of the phenomenon.

這個在西元前 3 萬年所繪製的洞穴壁畫，可能代表著最早觀察到此現象的紀錄。

But, it wasn't recorded in more detail until 2600 BC, when a Chinese manuscript described it as "strong lightning."

但是，直到西元前 2600 年時才一份來自中國的手稿具有更詳盡的紀錄，並把它描述為「強烈的光線」。

Most early attempts to explain the Aurora fell flat.

大部分早期試圖解釋極光為何形成的理論都是不正確的。

A drawing from 1570 AD attempted to illustrate it as a line of candles, hovering above the clouds.

一個西元 1570 年的畫作試圖將極光描述成一行行燭光，在雲上盤旋著。

In 1619, Galileo thought reflected sunlight was causing the light show, so he named it after the Roman goddess of the morning.

在 1619 年，伽利略認為極光的出現是因為太陽光的反射，所以他以羅馬早晨之神之名來命名極光。

It wasn't until the 20th century that Norwegian scientist Christian Berkland suggested molecules in the atmosphere were responsible for the light show.

直到 20 世紀，挪威的科學家克里斯琴．柏克蘭才提出大氣中的分子是促成極光顯現的原因。

The Aurora Borealis and its southern cousin, Aurora Australis, are generally located over ring-shaped regions, roughly 4,000km wide, which circle the North and South poles.

北極光以及它的好兄弟，南極光，大致上座落於這個環形區。整個環形區約 4000 公里寬，並包圍了北極和南極。

But when an Aurora is putting on a big show, the ring spreads over a much larger area.

但是正值極光極大期時，環形區會大幅向外擴張。

On rare occasions, Aurora Borealis can be seen as far south as Texas!

有時候，甚至南至德州都看得到北極光！

If you want to see an Aurora yourself, you can either travel north or south, or just wait for a particularly large Aurora.

如果你想要親自看看極光，你可以往北或往南去，或是等待一個規模特別大的極光。

You'll want a clear, dark night, and you should avoid heavily populated areas with a lot of light pollution.

你需要一個乾淨且深黑的夜晚，並且要避免人群眾多的地方，因為那裡有嚴重的光害。

Then, just look up and marvel!

接著，抬頭並感到驚艷吧！

I'm Sophie Bushwick, and that's your Countdown.

我是 Sophie Bushwick，這是今天的「倒數計時」。

If you like our show, visit the Spacelab Channel on Youtube, or follow us on twitter, @sa_spacelab, and if you've got any topics you'd like to see in the future, let us know in the comments.

如果你喜歡我們的節目，歡迎到 YouTube 的 Spacelab 頻道，或是在twitter上追蹤我們：@sa_spacelab，若你有任何想看的主題，可以留言讓我們知道。