未登录,请登录后再发表信息
最新评论 (0)
播放视频

为何冥王星不是行星?

Why is Pluto not a planet?

古往今来
Throughout the ages, the number of planets
太阳系中行星的数量起伏不定
in our solar system has gone up and down.
不过 这并不是因为行星突然的出现或消失
No, this is not because planets have suddenly appeared and disappeared,
只是因为
but rather due to how they
发现他们的方式不同
were discovered.
自远古时期 地球周边就有五大行星
Since antiquity, there were five planets beyond Earth,
它们都是肉眼可见的
which are the ones visible to the naked eye,
水星 金星 火星 木星和土星
Mercury, Venus, Mars, Jupiter and Saturn.
古希腊人曾把太阳和月亮列入他们的行星分类中
The ancient Greeks added the Sun and the moon to their list of planets,
但这一想法并未被理解接受
but that idea never really caught on.
在18世纪末 人们发现了天王星
In the late 1700s, Uranus was discovered,
在那时算是行星大变革 因为除了能看见的五大行星外
which was revolutionary at the time as no-one
人们认为不会有更多的行星存在
considered there could be more planets beyondthe visible five.
自此以后 越来越多的行星被发现
After this discovery, more and more planet candidates were being found,
像谷神星 灶神星 智神星和婚神星
like Ceres, Vesta,Pallas and Juno
这些都是在我们所谓小行星带上发现的
which are all found in what we now know
或者是在火星和木星之间
as the asteroid belt, or the large belt of asteroids
的大型的小行星带发现的
between the orbit of Mars and Jupiter.
19世纪初的科学教科书上 他们被统称为行星
In science textbooks in the early 1800s, they were all listed as planets.
到了19世纪中期 海王星也被发现了
In the middle of the 1800s, Neptune was discovered,
仅仅数十年期间
and within just a few decades,
我们发现了相当多的行星
we had quite a list of planets on our hands.
我们现在知道的八大行星
At that time there wasn’t a clear distinction
和众多被发现的大型小行星
between the eight planets we know today and
在当时并没有明显的差别
the large asteroids that were being discovered.
直到1860年 又发现了100多个小行星
By the 1860s, over one hundred asteroids had been found,
他们也终于被给予了
and they were finally given their
不同行星分类
own distinct classification as asteroids.
除了他们都在天空中运动这一事实
Asteroids were described as objects that couldn’t be distinguished from stars,
行星是很难与恒星区分开来的
bar the fact that they move across the sky.
所以即使在一百多年前
So even one hundred or so years ago,
我们严格讲都是降级的星球
we were ruthless and demoted planets.
许多人感觉到
A lot of people in the world feel
冥王星好像受到了不公平对待
like Pluto has been hard done by.
但是冥王星是被严格地按照大行星看待的
But Pluto has been treated just as harshly as the large asteroids.
冥王星是在1930年被发现
In 1930, Pluto was discovered,
这巨大又遥远的天体的发现使科学家们十分兴奋
and with the excitement of finding something so large and distant,
随后它被分类成了行星
it was classified as a planet.
然而 在几十年内
Although,within a few decades,
发现它并不符合行星的
it was discovered that it didn’t follow the conventions of
传统定义
traditional planet.
我们所定义的行星拥有圆形轨道
The planets we know have circular orbits than align roughly
且大致与太阳系的平面对齐
with the plane of the solar system.
另一方面 冥王星的
Poluto, on the other hand,
轨道和太阳系有一定角度 且在一年中有些时候
orbits at an angle to the solar system, and its orbit is so elliptical
它的轨道是椭圆的
that at some points during its year,
它比海王星更靠近太阳
it’s closer to the Sun than Neptune.
但因它很独特 所以称之为行星并无不妥
But it was also unique, so no-one minded it being called a planet.
但是到了20世纪70年代
But then, in the 1970s,
科学家发现冥王星变得比预想的要小很多
Pluto was discovered to be a lot tinier than expected.
结果表明它的质量只有月球的六分之一
It turned out that its mass is only one sixth of our moon.
关于冥王星的疑惑一直持续到90年代
Trouble continued for Pluto in the 90s,
直到望远镜技术取得巨大进步
when telescopic technology had greatly increased,
又在冥王星的轨道上和附近有了新发现
and other worlds were being discovered in and around the orbit of Pluto.
就和小行星带的发现一样
Just like the discovery of the asteroid belt,
很快就能清楚地发现在海王星的轨道之外
it quickly became apparent that there was another belt beyond
有一个被称为柯伊伯星带的小行星带
the orbit of Neptune, now known as the Kuiper belt.
更多的星体不断被探索到
These objects are still being discovered,
其中最著名的有厄里斯 塞德娜 妊神星 和鸟神星
the most famous ones being Eris, Sedna, Haumea and Makemake.
实际上他们的发现远不止这些 请看这张表
But seriously, they have found a lot, just look at this list!
在2006年 国际天文联合会觉得必须做点什么
In 2006, the International Astronomical Union knew that something had to be done.
他们最终确定行星的归类条件有
They finally classified a planet as a celestial object that:
(a)绕太阳公转轨道运行
(a) is in orbit around the Sun
(b)自身质量必须足够大 来克服刚体力以
(b) has sufficient mass for its self-gravityto overcome rigid body forces so that it assumes
达到流体静力平衡的近球体形状
a hydrostatic equilibrium or which means a nearly round shape
(c)必须清除轨道附近的其他天体
And (c)has cleared the neighbourhood around its orbit.
尽管冥王星符合前两条分类条件
So although Pluto fits the bill for the first two categories,
但由于它位于柯伊伯行星带
because it lies in the Kuiper Belt,
它没有清除轨道 所以不是一颗行星
it has not cleared its orbit and thus is not a planet.
而被称之为矮行星
It is instead known as a dwarf planet,
除了没有大规模地清除轨道
which is the almost the same except it’s not massive
它和行星几乎一样
enough to have cleared its orbit.
我们不应该把这看作是对冥王星的歧视
We shouldn’t see this as a sleight against Pluto,
正因为这些新发现
but rather because of these new discoveries,
我们有了对天体新的全套分类
we have a whole new category of celestial objects to learn about!
也因为有了分类的变化
Also because of the classification change,
曾被称为行星的谷神星有了一线希望
there is a silver lining for the once-planet Ceres
它被证明是一颗矮行星而不是小行星
It got promoted from being an asteroid to become a dwarf planet!
感谢观看!
Thanks for watching!
你着迷于冥王星吗?
Are you a fan of Pluto?
那么你可能会喜欢我们的《新视野》节目
Then you’ll probably like this video about the New Horizons mission there!
非常感谢大家特别是我的赞助商们
A big thank you especially to my Patrons who are helping support the channel.
是你们让我做得这么好
I couldn’t do it without you!
如果你想通过其他方式支持我们频道
If you want to help support the channel in other ways,
分享和点赞是非常好的方式
Sharing and liking gose a long way
祝一切安好
All the best!
我们下次再见
And see you next time.

发表评论

译制信息
视频概述

为何冥王星不是行星

听录译者

收集自网络

翻译译者

Feeling🍉

审核员

审核员SX

视频来源

https://www.youtube.com/watch?v=MPMIpp7Q2k0

相关推荐