未登录,请登录后再发表信息
最新评论 (0)
播放视频

如何寻找太阳系外的行星

How to Find an Exoplanet

克莱德·汤博花了半年时间
It took Clyde Tombaugh half a year
手动对比了含有200多万颗
of manually looking at photographic
恒星的底片
plates, contains over two million stars
才发现了冥王星
before he discovered Pluto.
这还是在太阳系内
and its in our own solar system.
那么在地球上如何去发现一颗围绕遥远恒星旋转的行星呢
So how on earth, does one find a planet orbiting a distant star?
你可以直接观察
You could just look,
但恒星离我们太过遥远
but stars are so far away,
而且亮度比行星高很多
and so bright compared to their planets,
直接观察很难发现环绕恒星的行星
that its really hard to just look at one, and see a planet orbiting it.
通过观察直接发现的外星系行星
Direct discovery of new exoplanets by
前提条件是
just looking, is essentially limited to
恒星离得不远
relatively nearby stars,
而它的行星很大 且离他们很远
with very large planets, very far away from them.
比如木星的十倍大而且绕行轨道也要很大
Think 10 times the size of jupiter, and an orbit at least as big.
大部分系外行星的发现
The vast majority of exoplanets,
都是通过间接观察他们对母星的影响
have been found indirectly, by observing their effects on their parents stars.
比如 一个行星经过一个恒星时
For example, a planet passing in front of a star will make
会在短时间内让恒星的亮度降低一些
that star darker for a little while.
而亮度降低的量会告诉你这颗行星的大小
and the amount it darkens, will tell you about the size of the planet, relative to the size of the star.
当然前提是行星必须刚好穿过我们和恒星之间的时候才能观察到
of course this only works if the planets orbit is tilted perfectly to pass between us and its star.
只有不到1%的行星拥有这样的绕行轨道
and on average less than 1% of earth like planets will have this convenient orbital orientation.
我们已经通过卫星这样搜索到了
We have managed to find a lot of exoplanets this way,
许多系外行星
by exhaustive satellite searches.
但你也可以观察行星对自己恒星的影响
but you could instead have a look at the effect planets have on the motion of stars.
我们知道 行星不绕恒星旋转
as we know, planets don’t orbit stars.
而是都绕他们的联合中心旋转
Rather, both orbit around their combined centre of mass.
恒星质量很大 所以联合中心在恒星内部
Stars are so heavy, so often the centre of mass is inside the star,
这样恒星几乎是不动的
but the star will nonetheless be moving.
相对于我们 在恒星的速度下
That motion manifests itself as a teeny tiny wobble,
它的运动表现为极其微小的摆动
in the velocity of the star relative to us.
我们可以通过仔细的测量
which we determine by carefully measuring the red or blue doppler shift
恒星发出的光当中的褐色光和蓝色光来发现
of the stars light
这两种间接方法都能有效地发现
both these indirect methods are most effective at finding big planets,
靠近恒星的大行星
close to their stars,
因为速度的影响以及光量的影响比较大
because the speeds involved, and the amount of light blocked
同时也因为靠近的行星绕行的周期短
are greater, and also because close planets orbit more often
所以我们不需要等待太久就能观察它们的影响
so we don’t have to wait as long to notice their effects.
还有其他更复杂更精确的方法
There are other more complicated and fancy methods which can find planets
用来发现以上两种方法还难发现的行星
which are harder to notice by a star wobbling or star light blocking
到2014年为止 这些方法帮助人们
and all of these together have helped to discover
发现了超过1800颗
more than 1800 exoplanets
系外行星
as of 2014.
抱歉冥王星 你被排除在外了
Sorry pluto, you’ve been Ex-ed out!
这个视频由Audible提供
This video is brought to you in part by Audible.com,
Audible是领先的有声书提供平台
The leading provider of audio books across all types of literature, including
平台涵盖小说 非小说 杂志期刊等文学作品
fiction, non-fiction and periodicals.
如果你去Audible网站的分钟物理专区
If you go to audible.com/minutephysics,
你可以免费下载你喜欢的有声书籍
you can try Audible out by downloading a free audiobook of your choice.
我想推荐一本
I would like to recommend the book ‘Foundation’.
艾萨克·阿西莫夫的《基地》
It’s the opening act of Isaac Asimov’s
本书是一系列作品的开端讲述星际文化即将迎来衰落
opening saga about the impending collapse of interstellar civilisation.
你可以在Audible分钟物理专区下载免费有声书
You can download your free audiobook at Audible.com/minutephysics
谢谢Audible提供支持 让这些视频得以呈现
and I would like to say thanks to Audible for helping me continue to make these videos.

发表评论

译制信息
视频概述

如何直接和间接观察到太阳系外的行星

听录译者

收集自网络

翻译译者

苏家Dier

审核员

审核团EM

视频来源

https://www.youtube.com/watch?v=AnX7ExBjrHw

相关推荐