冥王星是行星嗎？：英語精讀講義

Pluto, Planet or not?

冥王星，是不是行星？

Before we can answer this question, 文法

在回答這個問題之前，

we need to know what the word planet is for

我們需要知道「行星」這個詞是用來做什麼的，

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

這要把我們帶回古希臘時期，

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

當時他們把水星、金星、火星、木星、土星、

the Moon, and the Sun,

月球和太陽，

planets.

稱為行星。

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

基本上，如果在天空中移動並且很亮，那就是行星。

This is a terrible start for the word

這個詞的開端非常糟糕，

because one, it excludes Earth from the list,

因為首先，它把地球排除在名單之外，

and two, it groups wildly different things together.

其次，它把完全不同的事物歸為一類。

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

但希臘人不可能知道月球和土星有多大區別，

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

因為他們用來觀察宇宙的最好技術可悲地十分有限。

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

過了幾千年，直到勤勞的荷蘭人製造出第一批望遠鏡，

and astronomy became much more interesting.

天文學才變得有趣得多。

Astronomers could now confidently rearrange the solar system

現在，天文學家可以自信地重新排列太陽系，

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

這是一項沒人會反對的優雅科學進步，

and reclassify its parts,

並且重新分類其中的組成部分，

dropping the Sun and the Moon from the list of planets

將太陽和月球從行星名單中剔除，

and adding Earth.

並加入了地球。

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

現在，只要圍繞太陽運行，就是行星。

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

隨著時間推移，望遠鏡越來越先進，

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

每個新世紀都會帶來新行星的發現，

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

這就把我們帶到了熟悉的太陽系，

nine planets orbiting one star.

九大行星圍繞一顆恆星運行。

Looking at this model makes people wonder,

看著這個模型讓人不禁想問，

why do astronomers want to ditch Pluto? 用詞

為什麼天文學家想要拋棄冥王星？

The problem is pictures like this in textbooks are lies.

問題在於，教科書上這樣的圖片是謊言。

Well, not lies exactly, but unhelpful.

嗯，不完全是謊言，但毫無幫助。

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

它們給人一種印象，即行星大小差不多，

and evenly-ish spaced,

間距也相當均勻，

but the reality couldn't be more different. 文法

但現實卻截然不同。

Here, dear Terrans, is our home planet Earth,

親愛的地球人，這裡是我們居住的地球，

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

旁邊這是按正確比例縮放的木星。

Rather bigger than you probably thought.

比你想像的要大得多吧。

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

如果我們拿這張圖按照行星的正確大小進行調整，

it looks like this.

它看起來是這樣的。

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

除非你在全螢幕高畫質模式下觀看這段影片，

you might not be even able to see Pluto.

否則你甚至可能根本看不到冥王星。

So, size differences are vast.

所以，大小差異是巨大的。

and Pluto is the smallest by far, 片語搭配

冥王星是目前最小的，

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

但對於一顆行星來說，它不僅僅是小，

it's also smaller than seven moons.

它甚至比七顆衛星還要小。

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

海衛一、木衛二、我們的月球、木衛一、木衛四、土衛六和木衛三。

Even if you show the correct relative sizes, 文法

即使你展示了正確的相對大小，

the distances are still a problem.

距離仍然是個問題。

Think about it.

想一想。

If Jupiter was this close to Earth, 文法

如果木星離地球這麼近，

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

它在夜空中看起來就不會是一個小點，

but would be rather overwhelming.

而是相當具有壓倒性的存在。

So, it must be really far away,

所以，它一定離得很遠很遠，

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

這使得按比例繪製它成為一項挑戰。

If you want the length of a piece of paper

如果你想用一張紙的長度

to represent the distance from Mercury to Pluto,

來代表從水星到冥王星的距離，

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

那麼巨大的木星在這一頁上只有塵蟎那麼大，

and Pluto a bacterium.

而冥王星只有細菌那麼大。

But excluding Pluto from the planet club

但如果僅僅因為冥王星小且遠，就把其開除出行星俱樂部，

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

這個理由還不夠充分，

and quickly brings out the Pluto defenders. 片語動詞

並且會迅速招來冥王星辯護者的抗議。

In order to understand what Pluto really is, 文法

為了了解冥王星到底是什麼，

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

我們首先需要討論一顆你從未聽說過的行星，

Ceres.

穀神星。

Back in 1801,

回到1801年，

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

天文學家在火星和木星之間的巨大間隙中發現了一顆新行星。

It was a small planet,

它是一顆小行星，

but they loved it anyway and named it Ceres.

但他們仍然非常喜歡它，並將其命名為穀神星。

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

第二年，天文學家在同一區域發現了另一顆小行星，並命名為智神星。

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

幾年後，他們發現了第三顆，婚神星，

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

然後，有趣的是，又發現了第四顆，灶神星。

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

在幾十年的時間裡，孩子們學習的是太陽系有11顆行星。

But astronomers kept finding more and more of these objects 文法

但是天文學家不斷發現越來越多這樣的天體，

and became increasingly uncomfortable calling them planets

並且越來越覺得稱它們為行星不合適，

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

因為它們彼此之間的相似度遠高於它們兩邊任何一側的行星。

So, a new category was born, 慣用語

於是，一個新的分類誕生了，

asteroids in the asteroid belt.

小行星帶中的小行星。

And the tiny planets were relabeled,

那些微小的行星被重新分類，

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

這就是為什麼你從來沒有聽說過它們。

And it was a good decision, too,

這也是一個明智的決定，

as astronomers have now found hundreds of thousands of asteroids,

因為天文學家現在已經發現了數十萬顆小行星，

which would be a lot for a kid to memorize

如果它們都還是行星的話，

if they were all still planets.

孩子們要背的東西可就太多了。

Back to Pluto.

回到冥王星。

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

它於1930年被發現，成為了當時的第九大行星。

First estimates put Pluto about the size of Neptune,

最初的估計認為冥王星的大小與海王星差不多，

but with more observations,

但隨著更多觀測的進行，

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

這個估計值被不斷下調。

While Pluto shrank,

當冥王星「縮小」時，

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

天文學家開始在同一區域發現其他類似的天體在軌道上運行。

Sound familiar? 表達脈絡

聽起來很熟悉？

While school kids kept memorizing the nine planets,

當學童們還在繼續背誦九大行星時，

some astronomers grew uneasy about including Pluto

一些天文學家對將冥王星包含在內感到不安，

because the size estimates continued to shrink.

因為對它大小的估計還在不斷縮小。

They learned that Pluto is made mostly of ice,

他們了解到冥王星主要由冰組成，

and they continued to find lots and lots of icy objects

並且他們繼續發現許多許多冰冷的天體，

at the edge of the solar system just like Pluto.

就像冥王星一樣位於太陽系的邊緣。

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

只要沒人發現比冥王星更大的冰球，這個問題就可以被忽略，

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

而這正是2006年發現鬩神星時發生的事情。

Once again, astronomers recategorized the solar system

天文學家再一次重新對太陽系進行了分類，

and grouped these distant objects, including Pluto,

把包括冥王星在內的這些遙遠天體，

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

歸入了一個被稱為古柏帶的新區域。

And that's the story of Pluto,

這就是冥王星的故事，

a miscategorized planet that finally found its home, 慣用語

一顆被錯誤分類的行星終於找到了它的歸宿，

just like Ceres.

就像穀神星一樣。

But this story is really less about Pluto 文法

但這個故事其實不太關乎冥王星，

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

而是關於認識到「行星」這個詞其實並沒有多大幫助。

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

前四顆行星與後四顆行星完全不同，

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

所以把這八顆歸為一類甚至有點奇怪，

which is why they often aren't

這就是為什麼它們通常不被混為一談，

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

而是被分為類地行星和氣態巨行星。

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

而且現在我們的望遠鏡可以看到我們以外恆星周圍的行星，

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

並且我們已經發現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

以及模糊了行星和恆星界線的棕矮星，

the word planet becomes even less clear.

「行星」這個詞變得更加模糊不清了。

So, as we increase our knowledge of the universe,

所以，隨著我們對宇宙了解的增加，

the category of planet will probably continue to evolve

「行星」這一類別可能還會繼續演變，

or possibly fall out of favor entirely. 慣用語

或者完全被拋棄。

But for the time being, 片語搭配

但就目前而言，

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

對我們太陽系內物質進行分類的最好方式是一顆恆星，

eight planets,

八顆行星，

four terrestrial, four gas giants,

四顆類地行星，四顆氣態巨行星，

the asteroid belt,

小行星帶，

and the distant Kuiper belt, home to Pluto.

以及遙遠的古柏帶，冥王星的家。