On the darkest of nights, far from the lights of cars and cities, something special appears

在最黑暗的夜晚，遠離汽車和城市的燈光，出現了一些特別的東西。

in the sky. A cloudy white stripe of light stretches across the heavens! Ancient peoples

在天空中。一條條雲白色的光帶在天際延伸!古人

thought it looked like a stream of milk spilled across the sky, and so it is called 'the Milky

認為它像一股牛奶流灑在天空中，所以它被稱為'銀河。

Way.'

方式.'

The Milky Way that we see in the sky is part of a galaxy, or a huge collection of stars,

我們在天空中看到的銀河系是一個星系的一部分，或者說是一個巨大的恆星集合。

gas, dust, and other material. Galaxies are held together by gravity, much the same way

氣體、塵埃和其他物質銀河系是由引力連接在一起的，就像... ...

that our solar system is held together by the sun's gravity. The Milky Way is our galaxy,

我們的太陽系是由太陽的引力支撐起來的。銀河系就是我們的銀河系。

where our solar system is located, but the solar system is just a tiny piece of the galaxy.

我們的太陽系所在的地方，但太陽系只是銀河系的一小塊。

The Milky Way is enormous, at least 100,000 light-years across. A light year is how far

銀河系是巨大的，至少有10萬光年的直徑。一光年是指

light can travel in one year, nearly 6 trillion miles. In addition, the Milky Way has at least

光在一年內可以行駛近6萬億英里。此外，銀河系中至少有

200 billion stars and probably at least 100 billion planets in it.

2000億顆恆星，可能至少有1000億顆行星在其中。

Although it is massive, the Milky Way is not alone in the sky. It's part of a collection

雖然它是巨大的，但銀河系在天空中並不孤單。它是一個集合的一部分

of other galaxies called the local group, made of about 50 galaxies nearby to ours.

由其他星系組成，稱為在地星系群，由我們附近約50個星系組成。

The local group is estimated to be at least 10 million light years across. Outside of

據估計，當地群至少有1000萬光年的跨。外的

the local group, scientists estimate that at least 170 billion galaxies exist in the

在地組，科學家估計，至少有1700億個星系存在。

part of the universe that can be seen from Earth, and there is no way to know how many

宇宙的一部分，可以從地球上看到，並沒有辦法知道有多少個。

more there are beyond that.

除此之外還有更多的。

Galaxies come in many different shapes and sizes. They may have only a few million stars

星系有許多不同的形狀和大小。它們可能只有幾百萬顆恆星

in them or over a trillion. They may be elliptical, spiral, or irregular in shape.

中或超過一萬億。它們可能是橢圓形、螺旋形或不規則的形狀。

The Milky Way, like most known galaxies, is a spiral galaxy. Although no one knows what

銀河系和大多數已知星系一樣，是一個螺旋星系。雖然沒有人知道

the Milky Way actually looks like, because it is impossible to see all of it from the

銀河系的實際樣子，因為它是不可能看到所有的從它的

inside, careful observations of it as well as other galaxies has given scientists a good

內，對它以及其他星系的仔細觀察，讓科學家們對它有了很好的瞭解。

idea of its shape.

其形狀的想法。

There are four main parts in the Milky Way. In the center is the 'bulge,' or Galactic

銀河系有四個主要部分。中心是'隆起，'或銀河系。

center. This is a round bump in the center of the galaxy, about 10,000 light years across,

中心。這是銀河系中心的一個圓形凸起，直徑約1萬光年。

densely packed with stars and other material. Scientists believe that at the very center

密集著恆星和其他物質。科學家們相信，在最中心的地方

of the Milky Way is a giant black hole. The galactic center is the brightest part of the

銀河系的中心是一個巨大的黑洞。銀河系中心是銀河系中最亮的部分。

galaxy.

銀河系。

Next is the disk, a flattened region surrounding the bulge in the center. The disk is about

接下來是圓盤，是圍繞中心凸起的扁平區域。圓盤大約是

100,000 light-years across. It is filled with young stars, gas and dust, concentrated in

直徑10萬光年。它充斥著年輕的恆星、氣體和塵埃，集中於

the spiral arms. The spiral arms are part of the disk, and make the galaxy look a little

螺旋臂。螺旋臂是圓盤的一部分，使銀河系看起來有點兒...

like a pinwheel. Our solar system is located in one of the Milky Way's spiral arms, where

像一個針輪。我們的太陽系位於銀河系的一個螺旋臂中，在那裡

star systems are spread much farther apart than in the crowded Galactic Center.

與擁擠的銀河系中心相比，恆星系統分佈得更遠。

The last part of the Milky Way is the halo. The halo is a mostly spherical layer of old

銀河系的最後一部分是光環。光環是由老舊的球狀層組成的。

stars and star clusters that surrounds the main disk of the galaxy. The halo is very

恆星和星團，圍繞著銀河系的主盤。光環是非常

empty compared to the rest of the galaxy, with everything in it spread very far apart.

與銀河系的其他地方相比，空無一物，其中的一切都分佈在非常遙遠的地方。

Ancient Greek philosophers thousands of years ago first suggested that the Milky Way might

幾千年前的古希臘哲學家首次提出，銀河系可能是

be made of far away stars that were close together, but there was no way to prove this

是由相距很近的遠古恆星組成的，但沒有辦法證明這一點。

until the 1600s when the astronomer Galileo Galilei observed the Milky Way with his telescope

直到16世紀，天文學家伽利略-伽利萊用他的望遠鏡觀測銀河時為止

and discovered that it was, in fact, made of many, many faint stars. If you can find

並發現，它其實是由很多很多微弱的星星組成的。如果你能找到

somewhere to go that is very dark and far from the lights of cities and cars, you, too,

某處要去的地方，很黑，遠離城市和汽車的燈光，你，也。

can see the mysterious sight that inspired myths and legends for thousands of years - the

可以看到千百年來激發神話傳說的神祕景象--------。

Milky Way.

銀河系。