Are the Northern Lights dangerous? - Fabio Pacucci

譯者: Lilian Chiu 審譯者: Helen Chang

On September 1st, 1859, miners following the Colorado gold rush woke up

1859 年 9 月 1 日，

追著科羅拉多淘金熱的礦工

to another sunny day.

醒來時又是個好天氣。

Or so they thought.

或至少他們以為如此。

To their surprise, they soon discovered it was actually 1 am;

沒多久，他們驚訝地發現 此時是凌晨一點；

and the sky wasn’t lit by the Sun, but rather by brilliant drapes of light.

天空並不是被太陽照亮的，

而是明亮的光幕。

The blazing glow could be seen as far as the Caribbean,

遠從加勒比海都能看到這片強光，

leading people in many regions to believe that nearby cities had caught fire.

導致許多地區的人都相信

鄰近的城市著火了。

But the true cause of what would come to be known as the Carrington Event

這就是後來所知的卡靈頓事件， 而其背後的成因

was a solar storm— the largest in recorded history.

是太陽風暴—— 有記錄以來最大的一次。

Solar storms are one of many astrophysical phenomena caused by magnetic fields.

有許多天體物理現象都是由 磁場造成，太陽風暴也是其一。

These fields are generated by movements of electrically charged particles

這些磁場的成因， 是帶電荷的粒子移動，

like protons and electrons.

比如光子和電子。

For example, Earth’s magnetic field is generated by charged molten metals

舉例來說，

地球的磁場的產生是因為熔化的金屬

circulating in the planet's outer core.

在地球的外核中繞行。

Similarly, the Sun’s magnetic field is generated by large convective movements

太陽磁場產生的原因也很類似，

是組成星體的電漿中 大型的對流活動所造成。

in the plasma that composes the star.

As this plasma slowly swirls,

當電漿緩慢地旋轉時，

it creates areas of intense magnetic activity called sunspots.

會造成一些區域有劇烈的磁場活動，

稱為太陽黑子。

The magnetic fields that form near these regions

在這些區域附近形成的磁場

often become twisted and strained.

通常會扭曲變形。

And when they’re stretched too far, they snap into simpler configurations,

當它們延展得太過頭時，

就會破裂開成為更簡單的結構，

releasing energy that launches plasma from the Sun’s surface.

釋放出能源，造成 電漿從太陽表面射出。

These explosions are known as coronal mass ejections.

這些爆炸就是「日冕物質拋射」。

The plasma— mostly made of protons and electrons— accelerates rapidly,

電漿——大部分 由光子和電子組成——

會快速加速。

quickly reaching thousands of kilometers per second.

很快就達到每秒鐘數千公里。

A typical coronal mass ejection covers the distance between the Sun and the Earth

典型的日冕物質拋射 只要花幾天的時間

in just a couple of days,

就能達到地球，

flowing along the magnetic field that permeates the solar system.

它會沿著散布在太陽系 各處的磁場流動。

And those that cross the Earth’s path are drawn to its magnetic field lines,

而經過地球路徑的拋射

則會被其磁場線給拉過去，

falling into the atmosphere around the planet’s magnetic poles.

在地球的磁極附近落入大氣當中。

This tidal wave of high-energy particles excites atmospheric atoms

這些高能粒子潮波

會激發大氣中的原子，如氧及氮，

such as oxygen and nitrogen,

causing them to rapidly shed photons at various energy levels.

造成它們在各能階 快速放射出光子。

The result is a magnificent light show we know as the auroras.

結果就是壯麗的亮光秀， 即我們所知道的極光。

And while this phenomenon is usually only visible near the Earth’s poles,

雖然這種現象通常只有 在地球極地附近才能看見，

strong solar storms can bring in enough high energy particles

但強力的太陽風暴 會帶來足夠的高能粒子，

to light up large stretches of the sky.

點亮大片的天空。

The magnetic fields in our solar system are nothing

我們太陽系中的磁場 和深太空的磁場相比，

compared to those found in deep space.

可說是小巫見大巫。

Some neutron stars generate fields 100 billion times stronger

有些中子星所產生的磁場，

是太陽黑點磁場的一千億倍。

than those found in sunspots.

And the magnetic fields around supermassive black holes

且，在超大質量黑洞附近的磁場

expel jets of gas that extend for thousands of light years.

產生的噴流可以達數千光年之遠。

However, on Earth, even weak solar storms can be surprisingly dangerous.

然而，在地球上，

即使是很弱的太陽風暴 也有驚人的危險性。

While the storms that reach us are generally harmless to humans,

雖然到達地球的風暴一般對人無害，

the high-energy particles falling into the atmosphere

落入大氣當中的高能粒子

create secondary magnetic fields,

會造成次生磁場，

which in turn generate rogue currents that short-circuit electrical equipment.

次生磁場則會產生猛烈的電流，

讓電子設備短路。

During the Carrington Event,

在卡靈頓事件發生時，

the only widespread electrical technology was the telegraph.

唯一普及的電子技術就是電報。

But since then, we've only become more dependent on electrical systems.

但在那之後，我們更加依賴電子系統。

In 1921, another powerful solar storm caused telephones

1921 年，

另一場強大的太陽風暴造成

全球各地的電話和電報設備燒壞。

and telegraph equipment around the globe to combust.

In New York, the entire railway system was shut down and fires broke out

在紐約，整個鐵路系統都停擺，

中央控制大樓還發生火災。

in the central control building.

Comparatively weak storms in 1989 and 2003

1989 年及 2003 年的 風暴相對比較弱，

turned off regions of the Canadian power grid

造成加拿大電力網的許多區域停電，

and damaged multiple satellites.

也損壞了數個衛星。

If we were hit by a storm as strong as the Carrington Event today,

如果現今我們面臨 卡靈頓事件時那麼強的風暴，

it could devastate our interconnected, electrified planet.

我們這個相互連結的電氣化 星球可能會受到重挫。

Fortunately, we're not defenseless.

幸運的是，我們並非毫無防備。

After centuries of observing sunspots,

在觀察了太陽黑子數百年之後，

researchers have learned the Sun’s usual magnetic activity

研究者發現，太陽的磁場活動通常

follows an 11-year cycle,

是十一年一個循環，

giving us a window into when solar storms are most likely to occur.

讓我們能知道太陽風暴 可能發生的時間。

And as our ability to forecast space weather has improved,

且，隨著我們預測 太空天氣的能力更進步，

so have our mitigation measures.

我們用來緩和風暴的措施也進步了，

Power grids can be shut off in advance of a solar storm,

可以在太陽風暴來襲之前 先把電力網關閉，

while capacitors can be installed to absorb the sudden influx of energy.

也可以安裝電容器， 來吸收突然流入的能量。

Many modern satellites and spacecraft are equipped with special shielding

許多現代的衛星及太空船 也都裝備有特殊的屏障，

to absorb the impact of a solar storm.

可以吸收太陽風暴的衝擊。

But even with these safeguards,

但，即使有這些保護，

it’s hard to say how our technology will fare during the next major event.

還是很難說在下次重大事件時 我們的科技是怎樣的狀況。

It’s possible we’ll be left with only the aurora overhead

有可能，我們會只剩下頭上的極光

to light the path forward.

來照亮向前的路。