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You and I have talked a lot about space, haven't we?
你我谈了很多关于太空的事，不是吗?
We've learned about stars!
我们已经了解了恒星！
We found out all about comets and asteroids!
我们发现了彗星和小行星的所有秘密！
And we can name all eight of the planets in our solar system!
而且我们可以命名太阳系的八颗行星！
But have you ever thought about what's beyond our solar system?
但你曾想过太阳系以外是什么吗？
The sun is just a star, after all.
毕竟太阳只是颗恒星。
And it along with us and all the other planets aren't just floating around in space, all by ourselves.
它和我们以及其他所有行星都不是孤独地漂浮在太空中。
Oh no. Our solar system is part of something much, much bigger. A galaxy!
噢，不！我们的太阳系是某个更大集团的一部分，星系！
A galaxy is a huge bunch of stars that are clustered together in space.
星系是太空中聚集在一起的大堆恒星。
And the galaxy that our solar system is part of is called the Milky Way.
我们的太阳系是银河系的一部分。
The Milky Way is just full of stars!
银河系都是恒星！
How many? Well, do you know how much a thousand is?
有多少颗？你知道1000是多少吗？
A thousand looks like this.
1000这么多。
And if you take a thousand and multiply it by a thousand and multiply it by a thousand again.
如果你用1000乘以1000，再乘以1000，
That number is a billion.
就是十亿。
And there are billions of stars just in the Milky Way alone!
而银河系自己就有数十亿颗恒星！
In fact, there are so many stars in the Milky Way that we still don't know exactly how many there are.
事实上，银河系的恒星这么多，我们也不知道它到底有多少颗。
But scientists think that many of the other stars in our galaxy probably have planets on their own!
但科学家们认为，我们星系中的许多其他恒星可能有自己的行星！
And the Milky Way isn't the only galaxy!
银河系并不是唯一的星系！
Astronomers who study deep, distant space have found other galaxies, too!
研究遥远太空的天文学家也发现了其他星系。
More than you could count!
比你计算得还多!
To organize and study all of these galaxies,
天文学家为了整理和研究这些星系，
astronomers usually group them into three main types, depending on their shape.
通常根据形状把它们分成三种主要的类型。
There are spiral galaxies, elliptical galaxies and irregular galaxies.
螺旋星系、椭圆星系和不规则星系。
Spiral galaxies are in the shape of a pinwheel.
螺旋星系的形状像风车。
They have that shape because stars in a spiral galaxy are clumped into lines that curl outward.
它们有如此形状，是因为螺旋星系中的恒星会聚集成外卷的线条。
These lines are called the spiral arms.
这些线条被称为旋臂。
And the galaxy that you and I are in right now, The Milky Way galaxy, is a spiral galaxy!
你我所在的银河系就是螺旋星系！
Now, some spiral galaxies are just flat, like a pancake.
现在，一些螺旋星系是平的，就像煎饼一样。
But other spirals, including our own Milky Way,
但是其他的螺旋星系，包括我们的银河系，
have a large bulge in the middle that's made up of a big bunch of stars.
中间有一个大堆恒星组成的隆起。
The stars in the bulge are usually older stars,
隆起中的恒星通常是较老的恒星，
while younger stars are often found on the outer spiral arms of the galaxy.
而年轻的恒星经常出现在星系的外旋臂上。
Astronomers even know where our star, the sun, is in the Milky Way.
天文学家甚至知道我们的恒星太阳在银河系中的位置。
If you were way, way out in space, floating above our galaxy, and looked down at it,
如果你远离银河系，漂浮在上面俯瞰它，
you'd find the sun right about here, near the middle of one of the spiral arms.
就会发现太阳在这里，接近一个旋臂的中间位置。
Now, another common kind of galaxy is called an elliptical galaxy.
另一种常见类型的星系叫做椭圆星系。
Elliptical galaxies are shaped like an ellipse, or an egg shape.
椭圆星系的形状像椭圆或鸡蛋。
And instead of being flat with a bulge in the middle, these galaxies are all bulge.
这种星系都是隆起，而不是只有中间隆起。
They tend to have mostly older stars in them.
他们大多是年老的恒星。
And stars in an elliptical galaxy are really close together,
椭圆星系中的恒星非常接近，
which makes the middle of the galaxy look like one, giant, bright star.
使得星系中间看起来像一颗巨大明亮的星星。
The last common type of galaxy is an irregular galaxy.
最后一种常见的星系类型是不规则星系。
Irregular means "not regular", and these kinds of galaxies don't have a definite, regular shape.
Irregular意为“不规则”，这种类型的星系没有确切的规则形状。
Instead, these clusters of stars can take all kinds of different shapes, like this or this, or even this.
这些星系团可以有各种不同的形状，比如这个，或这个，甚至是这个。
There are tons of other galaxies out there to learn about,
我们还有很多其他的星系要了解，
and scientists are discovering new ones all the time.
科学家们一直在发现新的星系。
So the next time you're out at night, gazing at the sky,
所以你下次晚上外出看夜空时，
remember that you and the Earth and the whole solar system are part of something bigger. A galaxy!
记住，你、地球以及整个太阳系都是更大的集团——星系的一部分！
Thanks for joining us today!
感谢您的收看！
If you have a question for us about space or the Earth or anything at all,
如果你对太空、地球或任何事情有疑问，
just let us know by getting help from a grown up and leaving a comment a below.
找个大人帮忙在下方留言告诉我们，
Or send us an email at kids@thescishow.com.
或发邮件至kids@thescishow.com。
