冥王星是行星吗？：英语精读讲义

Pluto, Planet or not?

冥王星，是不是行星？

Before we can answer this question, 語法

在回答这个问题之前，

we need to know what the word planet is for

我们需要知道“行星”这个词是用来做什么的，

and that takes us back to the ancient Greeks 短語動詞

这要把我们带回古希腊时期，

who called Mercury, Venus, Mars, Jupiter, Saturn,

当时他们把水星、金星、火星、木星、土星、

the Moon, and the Sun,

月球和太阳，

planets.

称为行星。

Basically, if it moved across the sky and was bright, it was a planet. 語法

基本上，如果在天空中移动并且很亮，那就是行星。

This is a terrible start for the word

这个词的开端非常糟糕，

because one, it excludes Earth from the list,

因为首先，它把地球排除在名单之外，

and two, it groups wildly different things together.

其次，它把完全不同的事物归为一类。

But the Greeks couldn't know how different the Moon was from Saturn 語法

但希腊人不可能知道月球和土星有多大区别，

because the best technology they had to observe the universe was sadly limited.

因为他们用来观察宇宙的最好技术可悲地十分有限。

It would take several thousand years until the industrious Dutch made the first telescopes 語法

过了几千年，直到勤劳的荷兰人制造出第一批望远镜，

and astronomy became much more interesting.

天文学才变得有趣得多。

Astronomers could now confidently rearrange the solar system

现在，天文学家可以自信地重新排列太阳系，

an elegant scientific advance that no one could possibly object to 語氣意圖

这是一项没人会反对的优雅科学进步，

and reclassify its parts,

并且重新分类其中的组成部分，

dropping the Sun and the Moon from the list of planets

将太阳和月球从行星名单中剔除，

and adding Earth.

并加入了地球。

Now, if it orbited the Sun, it was a planet.

现在，只要围绕太阳运行，就是行星。

As time went on and telescopes got better and better, 短語搭配

随着时间推移，望远镜越来越先进，

each new century brought with it the discovery of a new planet, 短語搭配

每个新世纪都会带来新行星的发现，

which brings us to this familiar solar system, 短語動詞

这就把我们带到了熟悉的太阳系，

nine planets orbiting one star.

九大行星围绕一颗恒星运行。

Looking at this model makes people wonder,

看着这个模型让人不禁想问，

why do astronomers want to ditch Pluto? 用詞

为什么天文学家想要抛弃冥王星？

The problem is pictures like this in textbooks are lies.

问题在于，教科书上这样的图片是谎言。

Well, not lies exactly, but unhelpful.

嗯，不完全是谎言，但毫无帮助。

They give the impression that the planets are similar-ish in size 短語搭配

它们给人一种印象，即行星大小差不多，

and evenly-ish spaced,

间距也相当均匀，

but the reality couldn't be more different. 語法

但现实却截然不同。

Here, dear Terrans, is our home planet Earth,

亲爱的地球人，这里是我们居住的地球，

and this is Jupiter next to it at the correct scale.

旁边这是按正确比例缩放的木星。

Rather bigger than you probably thought.

比你想象的要大得多吧。

If we take this diagram and adjust for the correct sizes of the planets,

如果我们拿这张图按照行星的正确大小进行调整，

it looks like this.

它看起来是这样的。

Unless you're watching the video in full-screen HD mode, 語法

除非你在全屏高清模式下观看这段视频，

you might not be even able to see Pluto.

否则你甚至可能根本看不到冥王星。

So, size differences are vast.

所以，大小差异是巨大的。

and Pluto is the smallest by far, 短語搭配

冥王星是目前最小的，

but it's not just small for a planet, 語法

但对于一颗行星来说，它不仅仅是小，

it's also smaller than seven moons.

它甚至比七颗卫星还要小。

Triton, Europa, our own Moon, Io, Callisto, Titan, and Ganymede.

海卫一、木卫二、我们的月球、木卫一、木卫四、土卫六和木卫三。

Even if you show the correct relative sizes, 語法

即使你展示了正确的相对大小，

the distances are still a problem.

距离仍然是个问题。

Think about it.

想一想。

If Jupiter was this close to Earth, 語法

如果木星离地球这么近，

it wouldn't look like a dot in the night sky,

它在夜空中看起来就不会是一个小点，

but would be rather overwhelming.

而是相当具有压倒性的存在。

So, it must be really far away,

所以，它一定离得很远很远，

which makes drawing it to scale rather a challenge. 短語搭配

这使得按比例绘制它成为一项挑战。

If you want the length of a piece of paper

如果你想用一张纸的长度

to represent the distance from Mercury to Pluto,

来代表从水星到冥王星的距离，

then giant Jupiter would be the size of a dust mite on that page

那么巨大的木星在这一页上只有尘螨那么大，

and Pluto a bacterium.

而冥王星只有细菌那么大。

But excluding Pluto from the planet club

但如果仅仅因为冥王星小且远，就把其开除出行星俱乐部，

just for being tiny and far away isn't reason enough

这个理由还不够充分，

and quickly brings out the Pluto defenders. 短語動詞

并且会迅速招来冥王星辩护者的抗议。

In order to understand what Pluto really is, 語法

为了了解冥王星到底是什么，

we need to first discuss a planet you've never heard of,

我们首先需要讨论一颗你从未听说过的行星，

Ceres.

谷神星。

Back in 1801,

回到1801年，

astronomers found a new planet in the huge gap between Mars and Jupiter.

天文学家在火星和木星之间的巨大间隙中发现了一颗新行星。

It was a small planet,

它是一颗小行星，

but they loved it anyway and named it Ceres.

但他们仍然非常喜欢它，并将其命名为谷神星。

The next year, astronomers found another small planet in the same area and named it Pallas.

第二年，天文学家在同一区域发现了另一颗小行星，并命名为智神星。

A few years later, they found a third one, Juno,

几年后，他们发现了第三颗，婚神星，

and then, funnily enough, a fourth one, Vesta. 短語搭配

然后，有趣的是，又发现了第四颗，灶神星。

And for several decades, children learned the 11 planets of the solar system.

在几十年的时间里，孩子们学习的是太阳系有11颗行星。

But astronomers kept finding more and more of these objects 語法

但是天文学家不断发现越来越多这样的天体，

and became increasingly uncomfortable calling them planets

并且越来越觉得称它们为行星不合适，

because they were much more like each other than the planets on either side. 語法

因为它们彼此之间的相似度远高于它们两边任何一侧的行星。

So, a new category was born, 習語

于是，一个新的分类诞生了，

asteroids in the asteroid belt.

小行星带中的小行星。

And the tiny planets were relabeled,

那些微小的行星被重新分类，

which is why you've never heard of them. 語法

这就是为什么你从来没有听说过它们。

And it was a good decision, too,

这也是一个明智的决定，

as astronomers have now found hundreds of thousands of asteroids,

因为天文学家现在已经发现了数十万颗小行星，

which would be a lot for a kid to memorize

如果它们都还是行星的话，

if they were all still planets.

孩子们要背的东西可就太多了。

Back to Pluto.

回到冥王星。

It was discovered in 1930, making it the then ninth planet. 語法

它于1930年被发现，成为了当时的第九大行星。

First estimates put Pluto about the size of Neptune,

最初的估计认为冥王星的大小与海王星差不多，

but with more observations,

但随着更多观测的进行，

that was revised down and down and down. 表達脈絡

这个估计值被不断下调。

While Pluto shrank,

当冥王星“缩小”时，

astronomers started to find other similar objects orbiting in the same zone.

天文学家开始在同一区域发现其他类似的天体在轨道上运行。

Sound familiar? 表達脈絡

听起来很熟悉？

While school kids kept memorizing the nine planets,

当学童们还在继续背诵九大行星时，

some astronomers grew uneasy about including Pluto

一些天文学家对将冥王星包含在内感到不安，

because the size estimates continued to shrink.

因为对它大小的估计还在不断缩小。

They learned that Pluto is made mostly of ice,

他们了解到冥王星主要由冰组成，

and they continued to find lots and lots of icy objects

并且他们继续发现许多许多冰冷的天体，

at the edge of the solar system just like Pluto.

就像冥王星一样位于太阳系的边缘。

This problem could be ignored as long as no one found an ice ball bigger than Pluto, 語法

只要没人发现比冥王星更大的冰球，这个问题就可以被忽略，

which is exactly what happened in 2006 with the discovery of Eris.

而这正是2006年发现阋神星时发生的事情。

Once again, astronomers recategorized the solar system

天文学家再一次重新对太阳系进行了分类，

and grouped these distant objects, including Pluto,

把包括冥王星在内的这些遥远天体，

into a new area called the Kuiper belt. 文化背景

归入了一个被称为柯伊伯带的新区域。

And that's the story of Pluto,

这就是冥王星的故事，

a miscategorized planet that finally found its home, 習語

一颗被错误分类的行星终于找到了它的归宿，

just like Ceres.

就像谷神星一样。

But this story is really less about Pluto 語法

但这个故事其实不太关乎冥王星，

than it is about realizing the word planet isn't very helpful.

而是关于认识到“行星”这个词其实并没有多大帮助。

The first four planets are nothing at all like the next four,

前四颗行星与后四颗行星完全不同，

so it's even a little weird to group these eight together,

所以把这八颗归为一类甚至有点奇怪，

which is why they often aren't

这就是为什么它们通常不被混为一谈，

and are separated into terrestrial planets and gas giants. 文化背景

而是被分为类地行星和气态巨行星。

And now that we have telescopes that can see planets around stars not our own, 語法

而且现在我们的望远镜可以看到我们以外恒星周围的行星，

and we've found rogue planets drifting in empty space 文化背景

并且我们已经发现了在太空中漂泊的流浪行星，

and brown dwarfs, objects that blur the very line between planet and star, 講解

以及模糊了行星和恒星界限的褐矮星，

the word planet becomes even less clear.

“行星”这个词变得更加模糊不清了。

So, as we increase our knowledge of the universe,

所以，随着我们对宇宙了解的增加，

the category of planet will probably continue to evolve

“行星”这一类别可能还会继续演变，

or possibly fall out of favor entirely. 習語

或者完全被抛弃。

But for the time being, 短語搭配

但就目前而言，

the best way to categorize the stuff in our solar system is into one star,

对我们太阳系内物质进行分类的最好方式是一颗恒星，

eight planets,

八颗行星，

four terrestrial, four gas giants,

四颗类地行星，四颗气态巨行星，

the asteroid belt,

小行星带，

and the distant Kuiper belt, home to Pluto.

以及遥远的柯伊伯带，冥王星的家。