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  • Have you seen this amazing video of the Northern lights?


  • 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!


  • I'm Sophie, and welcome to the Countdown.

    我是 Sophie,歡迎來到「倒數計時」。

  • What causes an aurora?


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


  • 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.


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


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


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


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


  • 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.


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


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


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


  • Navigation instruments like compasses become unreliable.


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


  • Auroras have fascinated humans for thousands of years.


  • 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.


  • 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.


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


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


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


  • Then, just look up and marvel!


  • 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。

Have you seen this amazing video of the Northern lights?


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