B1 中級 英國腔 30068 分類 收藏
It's proven to be one of the most divisive issues in modern science.
in one stroke, thousands of textbooks were out of date.
In my role as Public Astronomer here in Greenwich, I'm always being asked about Pluto.
Why was it reclassified?
And if it's not a planet anymore, then what on earth can it be?
Right from its discovery, Pluto seemed different from the other planets.
Here at the Royal Observatory, we have records going back for hundreds of years,
and somewhere, we should have a record of the discovery of Pluto.
1917, that's too early... 1987, much too late.
Clyde Tombaugh had been set the specific task of finding a planet,
so when he saw his moving point of light in 1930, what else was he going to think he'd found?
Here we have the President, Council, and Fellows at the Royal Astronomical Society sending the Lowell Observatory
their heartiest congratulations on the great discovery of the Trans-Neptunian planet.
But trouble was brewing from the word go.
Within weeks, Pluto's status was being called into question.
Its eccentric orbit and small mass set it apart from the other planets.
More importantly, some scientists argued that Pluto might not be alone.
Over the decades, our ideas about the formation of the Solar System developed.
It was suggested that the edge of the dust and gas cloud from which our planets formed
would have been too spread out to condense into planets.
Instead, they could be something very different.
Scientists reasoned that there could be hundreds of thousands of icy objects on the edge of the solar system
that had failed to be incorporated into one of the major planets.
They called this region the Kuiper Belt,
and Pluto's status as a planet started to be called into question.
On the fifth of January, 2005, came the fatal blow.
Scientists in California discovered another small moving point of light.
This was Eris, a world they believed was bigger than Pluto.
This was huge news.
The likelihood was, there could be many more large objects out there.
Scientists were faced with a choice: either open the doors to potentially hundreds of new planets,
or Pluto was for the chop.
In 2006, the International Astronomical Union put it to the vote,
and it wasn't good news for Pluto.
The IAU decided that a planet had to be an object in orbit around the sun,
that was massive enough for gravity to squeeze it into a spherical shape,
but also it had to be gravitationally dominant,
and that meant it must have cleared its surrounding region of other similarly sized objects,
but with everything else out there in the Kuiper Belt, this was Pluto's downfall.
So where did this leave Pluto?
The IAU decided to classify it as a dwarf planet.
To many, this would seem as a demotion, but I'm not so sure.
As a planet, it was the last gasp on the edge of the Solar System,
but now it's an exciting example of a brand new class of objects.
Whatever we learn from it will change the way we think about our corner of the galaxy.



冥王星為什麼不是行星?(Why is Pluto not a planet? - Sky at Night: Pluto Revealed Preview - BBC Four)

30068 分類 收藏
Joyce Lee 發佈於 2017 年 11 月 10 日    鍾昀倫 翻譯    James 審核
  1. 1. 單字查詢


  2. 2. 單句重複播放


  3. 3. 使用快速鍵


  4. 4. 關閉語言字幕


  5. 5. 內嵌播放器


  6. 6. 展開播放器


  1. 英文聽力測驗


  1. 點擊展開筆記本讓你看的更舒服

  1. UrbanDictionary 俚語字典整合查詢。一般字典查詢不到你滿意的解譯,不妨使用「俚語字典」,或許會讓你有滿意的答案喔