What is an aurora? - Michael Molina

壯麗的太陽風如何產生絢爛的極光—麥可·莫利納 (Michael Molina)

譯者: Regina Chu 審譯者: 瑞文Eleven 林Lim

Every second,

每一秒

one million tons of matter is blasted from the Sun

太陽噴發出一百萬噸的物質

at the velocity of one million miles per hour,

時速一百六十萬公里

and it's on a collision course with Earth!

這些物質還與地球相碰撞。

But don't worry,

但別擔心

this isn't the opening of a new Michael Bay movie.

這可不是變形金剛導演 麥可·貝的新科幻電影片頭

This is The Journey of the Polar Lights.

這是極光之旅

The northern and southern lights, also known as the aurora Borealis

北方的光與南方的光

分別稱為北極光

and aurora Australis, respectively,

及南極光

occur when high energy particles from the Sun

在來自太陽的高能粒子

collide with neutral atoms in our atmosphere.

與我們大氣層裡的 中性原子相撞時產生

會放射出能量

The energy emitted from this crash produces a spectacle of light

產生一種光的奇景

that mankind has marveled at for centuries.

數世紀來人類於此現象感到驚異

但是粒子的旅程可不是

But the particles' journey isn't just as simple

從太陽出發然後抵達地球這麼簡單

as leaving the Sun and arriving at Earth.

就像所有的開車長途旅行

Like any cross-country road trip, there's a big detour

常常繞來繞去

and nobody asks for directions.

也沒人要問路

Let's track this intergalactic voyage

來追蹤一下這個星際奇航吧

by focusing on three main points of their journey:

焦點放在此行的三個主要地方：

leaving the Sun, making a pit stop in the Earth's magnetic fields,

離開太陽

在地球的磁場短暫停留

and arriving at the atmosphere above our heads.

然後抵達我們頭上的大氣層

The protons and electrons creating the northern lights

產生北極光的質子與電子

從太陽的日冕出發

depart from the Sun's corona.

The corona is the outermost layer of the Sun's atmosphere

日冕是太陽

大氣的最外層

也是最高溫的地方

and is one of the hottest regions.

超高的熱度導致太陽的氫原子

Its intense heat causes the Sun's hydrogen and helium atoms to vibrate

及氦原子振動

將質子及電子分離

and shake off protons and electrons

as if they were stripping off layers on a hot, sunny day.

就好像在晴朗炎熱的日子 一件件脫掉衣服一樣

Impatient and finally behind the wheel,

急躁著想出門 最後終於上了駕駛座

these free protons and electrons move too fast

這些自由的質子及電子 運動速率極快

to be contained by the Sun's gravity

快到連太陽的重力都抓不住了

and group together as plasma, an electrically charged gas.

並集中在一起成為電漿

即帶電的離子化氣體

They travel away from the Sun as a constant gale of plasma,

他們從太陽出發

乘坐一陣陣的電漿風離開

一般稱為太陽風

known as the solar wind.

然而，地球為避免太陽風直接撞擊

However, the Earth prevents the solar wind from traveling straight into the planet

就讓他們繞道

by setting up a detour, the magnetosphere.

因而設下磁層

The magnetosphere is formed by the Earth's magnetic currents

磁層由地球的磁流形成

把圍繞在地球四周的粒子往外推

and shields our planet from the solar winds

屏蔽我們的星球 不被太陽風直接打到

by sending out the particles around the Earth.

太陽風所帶的離子

Their opportunity to continue the journey down to the atmosphere

在磁層無法負荷時

也可能往下進入大氣層

comes when the magnetosphere is overwhelmed by a new wave of travelers.

這情況稱為日冕質量拋射

This event is coronal mass ejection,

and it occurs when the Sun shoots out

發生於太陽射出

一個很大的電漿球進入太陽風

a massive ball of plasma into the solar wind.

When one of these coronal mass ejections collides with Earth,

當日冕質量拋射

與地球相撞時

it overpowers the magnetosphere and creates a magnetic storm.

使磁層超負荷

進而產生磁暴

The heavy storm stresses the magnetosphere until it suddenly snaps back,

強烈磁暴衝擊磁層

直到磁層突然恢復到原狀

很像過度伸展的橡皮筋

like and overstretched elastic band,

flinging some of the detoured particles towards Earth.

朝地球拋出一些繞道的粒子

The retracting band of the magnetic field drags them down to the aurora ovals,

往回縮的磁場

將這些粒子拉進極光橢圓區

which are the locations of the northern and southern lights.

即發生北極光和南極光的位置

After traveling 93 million miles across the galaxy,

旅行一億四千九百五十萬公里後

the Sun's particles finally produce their dazzling light show

太陽的粒子終於在朋友的幫助下

上演一場耀眼炫目的光秀

with the help of some friends.

地表上方 20-32 公里處

20 to 200 miles above the surface,

the electrons and protons meet up with oxygen and nitrogen atoms,

電子與質子

與氧及氫原子相遇

它們當然是相見歡

and they sure are happy to see each other.

The Sun's particles high five the atoms, giving their energy

太陽粒子與原子擊掌打招呼

將粒子的能量

to the Earth's neutral oxygen and nitrogen atoms.

傳給地球的中性氧原子及氫原子

When the atoms in the atmosphere are contacted by the particles,

當大氣層的原子

與粒子碰觸時

它們受激並射出光子

they get excited and emit photons.

Photons are small bursts of energy in the form of light.

光子是以光的形式呈現的 能量小爆發

The colors that appear in the sky

在天空中出現的極光顏色

取決於原子射出的光子的波長

depend on the wavelength of the atom's photon.

Excited oxygen atoms are responsible for the green and red colors,

激發態的氧原子產生

綠光及紅光

而激發態的氫原子則產生

whereas excited nitrogen atoms produce blue and deep red hues.

藍光及深紅色光

這些交互作用加起來

The collection of these interactions

就產生了北極光與南極光

is what creates the northern and southern lights.

The polar lights are best seen on clear nights

欣賞極光最佳時段 是在晴朗的夜晚

in regions close to magnetic north and south poles.

靠近地磁北極與 地磁南極的地方

Nighttime is ideal

夜間最理想

because the Aurora is much dimmer than sunlight

因為極光比陽光黯淡許多

and cannot be seen in daytime.

因此白天是看不到的

Remember to look up at the sky and read up on the Sun's energy patterns,

記得抬頭仰望天空

並研究一下太陽的能量週期

特別是太陽黑子及閃焰

specifically sunspots and solar flares,

as these will be good guides for predicting the auroras.

因為這些都是

預測極光的好指南