And we have finally proved just how these dazzling light shows happen.

而我們現在總算證明了這些令人眼花繚亂的燈光表演究竟是如何發生的。

Auroras appear in the upper atmosphere near the poles and they were first mentioned in texts thousands of years ago.

極光出現在兩極附近的高層大氣中，並在數千年前的文本記載中被首次提及。

But it wasn't until the late 1800's that a Norwegian physicist first made the connection between electric currents in Earth's magnetic field and auroras in the sky.

但直到十九世紀末，才有一位挪威物理學家首次將天空中的極光與地球磁場中的電流連結在一起。

And it's only been since the beginning of the 20th century that scientists have known the basics of how auroras work.

而到了二十世紀初，科學家們才總算知道了極光的基本運作原理。

Today, we know that all auroras begin with solar activity.

現在我們知道所有的極光都是從太陽活動開始的。

The sun puts out a continuous stream of charged particles called the solar wind.

太陽會發出被稱為太陽風的連續性帶電粒子流。

These energetic particles strike oxygen and nitrogen molecules in the atmosphere, bumping them up to an excited state.

這些高能量的粒子撞擊到氧氣和大氣中的氮氣分子後，將它們碰撞至激發狀態。

When they relax, the molecules emit photons that light up the night skies, producing beautiful auroras.

而當這些分子從激發狀態解放時，便會發出能照亮夜空的光子，產生出美麗的極光。

Occasionally, the sun will burp out a coronal mass ejection or solar flare, sending electrons slamming into Earth's magnetic field in what's called a geomagnetic storm.

太陽偶爾會噴出一大團日冕物質或太陽閃焰，在被稱為磁暴的過程中射出電子猛烈撞擊地球的磁場。

They're responsible for producing the most intense auroras.

最強烈的極光大多由此而生。

They disrupt the magnetic field lines, creating ripples that rebound back toward Earth known as Alfvén waves.

它們擾亂了磁力線，產生了會向地球反彈，被稱為阿爾文波的波紋。

And this is where the mystery starts. For the last 40 years, scientists have hypothesized that electrons can accelerate from space to Earth... and they do it by "surfing" on Alfvén waves.

而這正是謎團的開始。在過去的四十年裡，科學家們已經假設了電子可以從太空加速到地球... 並且是通過在阿爾文波上「衝浪」來實現的。

Any surfer will tell you that the key to catching a wave is paddling along with it.

所有衝浪好手都會告訴你，想要騎在海浪上的關鍵訣竅是要與浪一同向前划水。

If you paddle close to the speed of the wave, you'll be picked up and accelerated.

只要划水的速度接近波浪的速度，身體就會被抬起並加速。

The energy transfer from the wave to the electron happens through a phenomenon known as Landau damping.

從波到電子的能量轉移是通過一個被稱為蘭道阻尼的現象發生的。

But up until this point, scientists have struggled to prove this theory, so they did what scientists do and decided to recreate it in a lab.

但直到目前為止，科學家們一直難以證明這個理論，因此他們做了科學家最會做的事情：他們決定在實驗室中重新生成這個現象。

To see if electrons were accelerated by the electric field of an Alfvén wave, the team had to scale the vast distances of space into the confines of a lab.

為了觀察電子是否被阿爾文波的電場所加速，研究小組必須將太空規模大小的距離，限縮到實驗室的侷限下。

For this, they turned to UCLA's Large Plasma Device.

為此，他們求助於加州大學洛杉磯分校的大型等離子體裝置。

This nearly 20-meter-long cylindrical chamber creates a field of highly charged particles called plasma.

這個近二十公尺長的圓柱形的腔室，能創造出被稱為電漿的高度帶電粒子力場。

The team also had to develop new instruments and techniques to detect a very small population of electrons moving within a narrow range of velocities.

該團隊還必須開發新的儀器和技術，來檢測在一個狹窄的速度範圍內運動的微小電子群。

The experiment went down like this:

實驗是這樣進行的：

The plasma in the chamber forced electrons up and down the magnetic field.

實驗室中的電漿迫使電子在磁場中上下移動。

A specially designed antenna sent Alfvén waves down the chamber.

一個特別設計過的天線會發沿著腔室向下送出阿爾文波。

Further down the chamber, the scientists used the two new sensors they created to measure variations in the electric and magnetic field, and the electrons in the plasma.

再往下走，科學家們使用了他們為測量電場和磁場，以及電漿中電子的變化而設計出的兩個新感測器。

And they were right. The data showed a small population of electrons, like we're talking less than one in a thousand, surfing on epic Alfvén waves.

而他們的推測是正確的。數據顯示有大約不到千分之一的一小批電子，在史詩般的阿爾文波上衝浪。

So now that this hypothesis has been proven correct, what's next?

那麼，既然現在這個假設已經被證明是正確的了，下一步是什麼？

The techniques developed in this study can help scientists better understand other phenomena in space where particles are energized.

在這項研究中所開發的技術可以幫助科學家們更好地瞭解太空中粒子被激化賦能的其他現象。

Like how the sun's corona is heated to a million degrees, how cosmic rays get close to the speed of light, or how radiation belts, like the one near Earth, affect satellites that we depend on for communication and navigation.

比如太陽的日冕如何被加熱到一百萬度、宇宙射線如何加速至接近光速，或是如地球附近的輻射帶是如何影響到我們倚賴於進行通訊和導航的衛星的。

So next time you take a look at the dancing lights in the sky, remember the four-decade-long mystery, and how solving it will help us better understand the vast universe that surrounds us.

因此，下次抬頭看著天上舞動的光彩時，記住這個長達四十年的謎團，而解開它是如何幫助了我們更好地瞭解圍繞著我們的龐大宇宙。

If you find the magnetic field that helps produce Earth's auroras interesting, you should check out Amanda's video on Mars' magnetic field.

如果你覺得幫助產生出地球極光的磁場很有趣，那麼你可以看看 Amanda 介紹火星磁場的影片。

If there's a space breakthrough you'd like to see us cover, let us know in the comments below and as always, thanks for watching Seeker.

如果你有什麼想要我們報導的太空領域方面新的突破，請在下面的評論中告訴我們。一如既往地，感謝各位觀看 Seeker。