ABOUT THE SPEAKER
Anjali Tripathi - Astrophysicist
Anjali Tripathi explores planets to uncover the processes that make and destroy them.

Why you should listen

Even though Anjali Tripathi worked on NASA's Mars rovers in high school, the California native never expected to become an astronomer. Unlike the earthquakes she researched early on, astronomy seemed unconnected from daily life. As she has since discovered, exploring distant planets has a lot to do with life itself -- including the fate of the air we breathe. Using some of the most powerful telescopes and supercomputers, Tripathi studies how seemingly permanent planets change over time. She has pioneered the characterization of planet-forming environments and developed computer simulations to trace the 3D structure of planet atmospheres that are shrinking due to evaporation.

A natural teacher, Tripathi makes complex science concepts relevant and easy to understand. She believes that everyone can understand science -- even rocket science. She has partnered with the Smithsonian, Teach for America and others to increase scientific literacy and spread enthusiasm for the subject. Her engaging and humorous talks feature real world connections and unusual props, including a fully functioning Mars Pathfinder rover or full-size solar car.

Tripathi earned degrees in physics and astronomy from M.I.T., the University of Cambridge and Harvard University. Recognized as a promising American leader with a commitment to public service, Tripathi is a 2016-17 White House Fellow.


More profile about the speaker
Anjali Tripathi | Speaker | TED.com
TEDxBeaconStreet

Anjali Tripathi: Why Earth may someday look like Mars

安贾莉·特里帕蒂: 为什么地球有朝一日可能会变成火星

Filmed:
1,203,838 views

每分钟,都有400磅的氢气和将近七磅的氦气从地球大气层逃逸到外太空。天体物理学家安贾莉·特里帕蒂研致力于研究大气逃逸现象。在这个引人入胜、深入浅出的演讲中,她讨论了在未来(距今几十亿年后),这一过程可能会如何把我们的蓝色星球变为红色。 TEDx 由地区社群独立举办,演讲采取TED会议形式。更多相关信息:http://ted.com/tedx
- Astrophysicist
Anjali Tripathi explores planets to uncover the processes that make and destroy them. Full bio

Double-click the English transcript below to play the video.

00:12
So when you look out
at the stars明星 at night,
0
760
2975
当你望向夜空中的星星,
你会看到美得让人
00:15
it's amazing惊人 what you can see.
1
3760
1456
窒息的画面。
00:17
It's beautiful美丽.
2
5240
1456
但更令人惊叹不已的是
你看不见的部分,
00:18
But what's more amazing惊人
is what you can't see,
3
6720
3096
因为我们现在知道,
00:21
because what we know now
4
9840
1376
几乎每一颗恒星周围,
00:23
is that around every一切 star
or almost几乎 every一切 star,
5
11240
3376
都有一颗行星,
00:26
there's a planet行星,
6
14640
1256
或者可能有好几颗。
00:27
or probably大概 a few少数.
7
15920
1200
00:30
So what this picture图片 isn't showing展示 you
8
18120
2096
眼前这幅画面未能展现给你的,
是我们所知的
00:32
are all the planets行星 that we know about
9
20240
2136
宇宙中的所有行星。
00:34
out there in space空间.
10
22400
1400
00:36
But when we think about planets行星,
we tend趋向 to think of faraway远处 things
11
24280
3216
但当我们想到行星,
我们倾向于想到远在天边、
00:39
that are very different不同 from our own拥有.
12
27520
1856
与我们这颗行星
大不相同的那些行星。
但其实,我们就居住在一颗行星上。
00:41
But here we are on a planet行星,
13
29400
2416
关于地球,有太多令人惊奇的东西,
00:43
and there are so many许多 things
that are amazing惊人 about Earth地球
14
31840
3296
以至于我们会不远万里
去寻找类似的星体。
00:47
that we're searching搜索 far and wide
to find things that are like that.
15
35160
4176
而在寻找的过程中,
我们确实发现了惊人的现象。
00:51
And when we're searching搜索,
we're finding发现 amazing惊人 things.
16
39360
3496
但我想告诉大家一个
关于地球的不可思议的事实,
00:54
But I want to tell you
about an amazing惊人 thing here on Earth地球.
17
42880
4216
那就是每分钟,
00:59
And that is that every一切 minute分钟,
18
47120
2736
有400磅的氢气
01:01
400 pounds英镑 of hydrogen
19
49880
2416
和将近七磅的氦气
01:04
and almost几乎 seven pounds英镑 of helium
20
52320
2616
从地球上逃逸到太空中。
01:06
escape逃逸 from Earth地球 into space空间.
21
54960
2840
01:10
And this is gas加油站 that is going off
and never coming未来 back.
22
58800
3960
而这些气体一旦逃逸,
就不再返回。
01:15
So hydrogen, helium and many许多 other things
23
63440
3016
氢气、氦气和很多其他气体
组成了我们所知的地球大气层。
01:18
make up what's known已知
as the Earth's地球 atmosphere大气层.
24
66480
2856
大气层就是由这些气体
组成的一条细细的蓝线,
01:21
The atmosphere大气层 is just these gases气体
that form形成 a thin blue蓝色 line线
25
69360
3816
01:25
that's seen看到 here from
the International国际 Space空间 Station,
26
73200
3216
这就是宇航员从国际空间站
拍摄到的大气层。
01:28
a photograph照片 that some astronauts宇航员 took.
27
76440
2240
01:31
And this tenuous纤细 veneer单板 around our planet行星
28
79200
3376
而正是围绕我们行星的
这个气体薄层
让万物得以生生不息。
01:34
is what allows允许 life to flourish繁荣.
29
82600
2336
它使我们的行星
01:36
It protects保护 our planet行星
from too many许多 impacts影响,
30
84960
2856
免于遭受过多来自陨石
或类似物质的撞击。
01:39
from meteorites陨石 and the like.
31
87840
2016
而一个非常惊人的现象就是,
01:41
And it's such这样 an amazing惊人 phenomenon现象
32
89880
3776
01:45
that the fact事实 that it's disappearing消失
33
93680
2816
这些气体正在消失,
01:48
should frighten吓唬 you,
at least最小 a little bit.
34
96520
2800
这应该令你多少感到有些惊恐。
01:52
So this process处理 is something that I study研究
35
100160
3296
这就是我研究的内容,
01:55
and it's called atmospheric大气的 escape逃逸.
36
103480
2240
这一过程被称为“大气逃逸”。
01:58
So atmospheric大气的 escape逃逸
is not specific具体 to planet行星 Earth地球.
37
106680
4576
大气逃逸不仅仅在地球上发生,
在我看来,它正是
行星一词的部分含义,
02:03
It's part部分 of what it means手段
to be a planet行星, if you ask me,
38
111280
3736
因为不光是地球,
宇宙中的所有行星
02:07
because planets行星, not just here on Earth地球
but throughout始终 the universe宇宙,
39
115040
4336
02:11
can undergo经历 atmospheric大气的 escape逃逸.
40
119400
2576
都可能发生大气逃逸。
02:14
And the way it happens发生 actually其实 tells告诉 us
about planets行星 themselves他们自己.
41
122000
5400
而这一现象发生的方式,
揭露了行星自身的奥秘。
02:19
Because when you think
about the solar太阳能 system系统,
42
127920
2656
因为当你想到太阳系,
你可能会想到这幅画面——
02:22
you might威力 think about this picture图片 here.
43
130600
2040
02:25
And you would say, well,
there are eight planets行星, maybe nine.
44
133800
3416
你会说,嗯,总共有
八颗行星,也可能是九颗。
被这张图片搞晕的朋友们,
02:29
So for those of you
who are stressed强调 by this picture图片,
45
137240
2496
我再给你们添个东西。
02:31
I will add somebody for you.
46
139760
1376
(笑声)
02:33
(Laughter笑声)
47
141160
1216
借助“新视野号”太空探测器,
我们将冥王星加入了其中。
02:34
Courtesy礼貌 of New Horizons地平线,
we're including包含 Pluto冥王星.
48
142400
2880
我要强调一点,
02:38
And the thing here is,
49
146160
1216
为了方便演讲及介绍大气逃逸,
02:39
for the purposes目的 of this talk
and atmospheric大气的 escape逃逸,
50
147400
2736
我准备讨论一下冥王星,
02:42
Pluto冥王星 is a planet行星 in my mind心神,
51
150160
2016
02:44
in the same相同 way that planets行星
around other stars明星 that we can't see
52
152200
3936
不过那些围绕我们看不见的
其他恒星旋转的,
02:48
are also planets行星.
53
156160
1776
也同样是行星。
行星的一个基本特点
02:49
So fundamental基本的 characteristics特点 of planets行星
54
157960
2696
02:52
include包括 the fact事实 that they are bodies身体
55
160680
3016
就是它们自身由于重力的
02:55
that are bound together一起 by gravity重力.
56
163720
1816
束缚而形成一个整体。
所以行星仅仅是一大堆物质
02:57
So it's a lot of material材料
just stuck卡住 together一起
57
165560
2496
在吸引力的作用下聚在一起。
03:00
with this attractive有吸引力 force.
58
168080
1600
而这些行星体积庞大,重力也很大,
03:02
And these bodies身体 are so big
and have so much gravity重力.
59
170240
2856
因此它们是圆的。
03:05
That's why they're round回合.
60
173120
1296
你看所有这些行星,
03:06
So when you look at all of these,
61
174440
1616
03:08
including包含 Pluto冥王星,
62
176080
1216
包括冥王星,
都是圆的。
03:09
they're round回合.
63
177320
1200
03:11
So you can see that gravity重力
is really at play here.
64
179000
2736
所以你就可以看出,
重力确实在发挥作用。
但行星的另一个基本特点,
03:13
But another另一个 fundamental基本的
characteristic特性 about planets行星
65
181760
3296
是我们在这里看不到的。
03:17
is what you don't see here,
66
185080
1736
这是恒星——太阳,
03:18
and that's the star, the Sun太阳,
67
186840
2576
太阳系的所有行星都围绕它旋转,
03:21
that all of the planets行星
in the solar太阳能 system系统 are orbiting轨道 around.
68
189440
3120
03:25
And that's fundamentally从根本上 driving主动
atmospheric大气的 escape逃逸.
69
193200
3720
而这从根本上导致了大气逃逸。
03:29
The reason原因 that fundamentally从根本上 stars明星
drive驾驶 atmospheric大气的 escape逃逸 from planets行星
70
197760
5336
恒星从根本上导致
行星大气逃逸的原因在于,
恒星为行星提供粒子、光和热,
03:35
is because stars明星 offer提供 planets行星
particles粒子 and light and heat
71
203120
5376
而这些可以导致大气从行星逃逸。
03:40
that can cause原因 the atmospheres气氛 to go away.
72
208520
3096
如果你想象一个热气球,
03:43
So if you think of a hot-air热气 balloon气球,
73
211640
1816
或者看看这张图片中,
某个泰国节日的灯笼,
03:45
or you look at this picture图片
of lanterns灯笼 in Thailand泰国 at a festival,
74
213480
4136
你可以看到,热空气会将气体向上推。
03:49
you can see that hot air空气
can propel推进 gasses气体 upward向上.
75
217640
3496
如果你有足够的能量和热量,
03:53
And if you have enough足够 energy能源 and heating加热,
76
221160
2256
就像我们的太阳那样,
03:55
which哪一个 our Sun太阳 does,
77
223440
1336
那么这些仅仅受到
重力束缚的轻盈气体
03:56
that gas加油站, which哪一个 is so light
and only bound by gravity重力,
78
224800
3896
就会逃向太空。
04:00
it can escape逃逸 into space空间.
79
228720
1760
04:03
And so this is what's actually其实
causing造成 atmospheric大气的 escape逃逸
80
231600
3936
这就是导致大气逃逸的原因,
无论在地球上,还是在其他行星上——
04:07
here on Earth地球 and also on other planets行星 --
81
235560
2696
即发生于恒星提供的热量
04:10
that interplay相互作用
between之间 heating加热 from the star
82
238280
2696
和克服行星的重力之间的相互作用。
04:13
and overcoming克服 the force
of gravity重力 on the planet行星.
83
241000
3320
04:17
So I've told you that it happens发生
84
245000
1736
我已经讲过,这一过程
以每分钟400磅氢气
04:18
at the rate of 400 pounds英镑
a minute分钟 for hydrogen
85
246760
3336
和将近七磅氦气的速度发生。
04:22
and almost几乎 seven pounds英镑 for helium.
86
250120
2080
04:25
But what does that look like?
87
253040
1656
但是这个过程到底是什么样呢?
其实,早在20世纪80年代,
04:26
Well, even in the '80s,
88
254720
1816
我们拍摄的地球照片,
04:28
we took pictures图片 of the Earth地球
89
256560
1736
就是透过紫外线,
04:30
in the ultraviolet紫外线
90
258320
1456
利用美国国家航天局的
“动力探索者号”太空船完成。
04:31
using运用 NASA's美国航空航天局 Dynamic动态 Explorer探险者 spacecraft宇宙飞船.
91
259800
2896
这两张地球的照片,
04:34
So these two images图片 of the Earth地球
92
262720
1816
向我们展示了逃逸的氢气,
04:36
show显示 you what that glow辉光
of escaping逃逸 hydrogen looks容貌 like,
93
264560
3736
即图中红色的光。
04:40
shown显示 in red.
94
268320
1256
我们还可以看到其他气体的
样貌,如氧气和氮气,
04:41
And you can also see other features特征
like oxygen and nitrogen
95
269600
3616
即图中白色的微光
04:45
in that white白色 glimmer微光
96
273240
1456
所形成的一圈极光,
04:46
in the circle showing展示 you the auroras极光
97
274720
2336
还有赤道附近的一缕缕光亮。
04:49
and also some wisps缕缕 around the tropics热带.
98
277080
2896
这些图片无疑向我们展示了,
04:52
So these are pictures图片
that conclusively确凿 show显示 us
99
280000
3016
我们的大气层不只是
被牢牢束缚于地球表面,
04:55
that our atmosphere大气层 isn't just
tightly紧紧 bound to us here on Earth地球
100
283040
3696
它实际上还延伸到了遥远的太空中,
04:58
but it's actually其实
reaching到达 out far into space空间,
101
286760
3616
而且是以一种惊人的速度。
05:02
and at an alarming惊人 rate, I might威力 add.
102
290400
1920
05:05
But the Earth地球 is not alone单独
in undergoing经历 atmospheric大气的 escape逃逸.
103
293080
3816
但是地球不是唯一一个
正在经历大气逃逸的星球,
我们最近的邻居火星,比地球小得多,
05:08
Mars火星, our nearest最近的 neighbor邻居,
is much smaller than Earth地球,
104
296920
3456
所以它借以束缚大气的重量也轻得多。
05:12
so it has much less gravity重力
with which哪一个 to hold保持 on to its atmosphere大气层.
105
300400
3776
因此, 虽然火星有大气层,
05:16
And so even though虽然 Mars火星 has an atmosphere大气层,
106
304200
2216
但我们可以看到,
它比地球的大气层薄得多。
05:18
we can see it's much thinner更薄
than the Earth's地球.
107
306440
2216
看看火星的表面,
05:20
Just look at the surface表面.
108
308680
1456
我们看到了火山口,
这表明火星未曾有过可以阻止
05:22
You see craters陨石坑 indicating说明
that it didn't have an atmosphere大气层
109
310160
3456
这些撞击的大气层。
05:25
that could stop those impacts影响.
110
313640
1856
另外我们还看到,
火星是一颗“红色行星”,
05:27
Also, we see that it's the "red planet行星,"
111
315520
2776
而大气逃逸扮演的一个角色
05:30
and atmospheric大气的 escape逃逸 plays播放 a role角色
112
318320
2536
就是使火星成为红色。
05:32
in Mars火星 being存在 red.
113
320880
1576
这是因为我们认为,
火星曾经比现在湿润,
05:34
That's because we think
Mars火星 used to have a wetter多雨 past过去,
114
322480
3576
当水获得足够的能量,
它就分解为氢气和氧气,
05:38
and when water had enough足够 energy能源,
it broke打破 up into hydrogen and oxygen,
115
326080
4576
而氢气很轻,会逃逸到太空中,
05:42
and hydrogen being存在 so light,
it escaped逃脱 into space空间,
116
330680
3736
而留下来的氧气
05:46
and the oxygen that was left
117
334440
1936
则氧化使地表生锈,
05:48
oxidized氧化 or rusted生锈 the ground地面,
118
336400
1816
使地表变成了这种我们熟悉的锈红色。
05:50
making制造 that familiar
rusty生疏 red color颜色 that we see.
119
338240
3720
05:54
So it's fine to look at pictures图片 of Mars火星
120
342960
1936
所以当我们观察火星的图片,
我们有理由说,
大气逃逸可能曾经发生过。
05:56
and say that atmospheric大气的 escape逃逸
probably大概 happened发生,
121
344920
2456
不过,美国国家航天局
正在利用太空探测器MAVEN探测火星,
05:59
but NASANASA has a probe探测 that's currently目前
at Mars火星 called the MAVENMAVEN satellite卫星,
122
347400
4096
它的实际任务就是研究大气逃逸。
06:03
and its actual实际 job工作
is to study研究 atmospheric大气的 escape逃逸.
123
351520
3536
MAVEN即“火星大气与
挥发物演化”太空船。
06:07
It's the Mars火星 Atmosphere大气层
and Volatile挥发物 Evolution演化 spacecraft宇宙飞船.
124
355080
4576
探测传回的图片非常类似于
06:11
And results结果 from it have already已经
shown显示 pictures图片 very similar类似
125
359680
3656
我们在地球上看到的景象。
06:15
to what you've seen看到 here on Earth地球.
126
363360
1896
我们早已知道,火星一直在失去大气,
06:17
We've我们已经 long known已知 that Mars火星
was losing失去 its atmosphere大气层,
127
365280
2496
但我们这里有一些令人震惊的图片。
06:19
but we have some stunning令人惊叹 pictures图片.
128
367800
1776
比如在这张图中,
我们可以看到,红色圆圈
06:21
Here, for example,
you can see in the red circle
129
369600
3136
就是火星的轮廓;
06:24
is the size尺寸 of Mars火星,
130
372760
1496
而蓝色的部分,
就是从火星上逃逸的氢气,
06:26
and in blue蓝色 you can see the hydrogen
escaping逃逸 away from the planet行星.
131
374280
4176
它延伸到了火星自身尺寸
十多倍的距离之外,
06:30
So it's reaching到达 out more than 10 times
the size尺寸 of the planet行星,
132
378480
3536
这一距离,足以使氢气
不再受到火星引力的束缚,
06:34
far enough足够 away that it's
no longer bound to that planet行星.
133
382040
2696
于是它逃逸到了太空中。
06:36
It's escaping逃逸 off into space空间.
134
384760
1976
这帮助我们验证了我们的观点,
06:38
And this helps帮助 us confirm确认 ideas思路,
135
386760
2216
即通过氢气的逃逸来解释
为什么火星是红色的。
06:41
like why Mars火星 is red,
from that lost丢失 hydrogen.
136
389000
2760
但是氢气不是火星丧失的唯一气体。
06:44
But hydrogen isn't
the only gas加油站 that's lost丢失.
137
392520
2576
我提到了地球上的氦气,
以及一些氧气和氮气,
06:47
I mentioned提到 helium on Earth地球
and some oxygen and nitrogen,
138
395120
3176
而通过MAVEN我们也可以
观察从火星逃逸的氧气。
06:50
and from MAVENMAVEN we can also look
at the oxygen being存在 lost丢失 from Mars火星.
139
398320
3776
我们可以看到,由于氧气更重,
06:54
And you can see
that because oxygen is heavier较重,
140
402120
2456
它不会逃逸到像氢气那么远的距离,
06:56
it can't get as far as the hydrogen,
141
404600
3136
但它仍然向火星之外逃逸。
06:59
but it's still escaping逃逸
away from the planet行星.
142
407760
2176
可以看到氧气并不是
全部集中在红色圆圈里。
07:01
You don't see it all confined受限
into that red circle.
143
409960
3080
07:05
So the fact事实 that we not only see
atmospheric大气的 escape逃逸 on our own拥有 planet行星
144
413800
4016
我们不仅在自己的行星上
能看到大气逃逸,
还可以发射太空船,
在其他地方研究这一现象,
07:09
but we can study研究 it elsewhere别处
and send发送 spacecraft宇宙飞船
145
417840
3616
这让我们得以了解行星的过去,
07:13
allows允许 us to learn学习
about the past过去 of planets行星
146
421480
3096
乃至行星的概况,
07:16
but also about planets行星 in general一般
147
424600
2256
以及地球的未来。
07:18
and Earth's地球 future未来.
148
426880
1776
因此,我们了解未来的一个途径
07:20
So one way we actually其实
can learn学习 about the future未来
149
428680
2656
就是去研究不可见的遥远行星。
07:23
is by planets行星 so far away
that we can't see.
150
431360
3080
07:27
And I should just note注意 though虽然,
before I go on to that,
151
435440
3056
在我继续讲下去之前,
我应该强调一点,
我不打算给你们展示
像这样的冥王星图片,
07:30
I'm not going to show显示 you
photos相片 like this of Pluto冥王星,
152
438520
2456
这可能让你们有点失望,
07:33
which哪一个 might威力 be disappointing令人失望,
153
441000
1416
不过这是因为我们还没有图片。
07:34
but that's because we don't have them yet然而.
154
442440
2016
但是“新地平线”任务正在研究大气逃逸,
07:36
But the New Horizons地平线 mission任务
is currently目前 studying研究 atmospheric大气的 escape逃逸
155
444480
3256
也就是冥王星失去的大气。
07:39
being存在 lost丢失 from the planet行星.
156
447760
1336
所以继续关注,等待结果吧。
07:41
So stay tuned调整 and look out for that.
157
449120
1720
07:43
But the planets行星
that I did want to talk about
158
451560
2136
我原本想谈论的行星
被称为凌日系外行星。
07:45
are known已知 as transiting过境 exoplanets系外行星.
159
453720
2296
任何一个围绕太阳以外的
恒星旋转的行星
07:48
So any planet行星 orbiting轨道 a star
that's not our Sun太阳
160
456040
3776
都被称为外部行星,或系外行星。
07:51
is called an exoplanet太阳系外行星,
or extrasolar太阳系 planet行星.
161
459840
2936
而我们称之为“凌日”的这些行星
07:54
And these planets行星 that we call transiting过境
162
462800
2456
有一个特点,
07:57
have the special特别 feature特征
163
465280
1256
那就是如果你观察这颗恒星的中央,
07:58
that if you look
at that star in the middle中间,
164
466560
2096
你会看到它其实在闪烁。
08:00
you'll你会 see that actually其实 it's blinking闪烁.
165
468680
2376
而它闪烁的原因,
08:03
And the reason原因 that it's blinking闪烁
166
471080
1856
就是一直都有行星从那里经过,
08:04
is because there are planets行星
that are going past过去 it all the time,
167
472960
4016
08:09
and it's at special特别 orientation方向
168
477000
2136
而且遵从特定的轨道,
这样行星就挡住了来自恒星的光,
08:11
where the planets行星 are blocking闭塞
the light from the star
169
479160
2776
于是我们就看到了闪烁的光。
08:13
that allows允许 us to see that light blinking闪烁.
170
481960
2280
08:16
And by surveying测量学 the stars明星
in the night sky天空
171
484960
2856
通过在夜空中观测这些恒星的
08:19
for this blinking闪烁 motion运动,
172
487840
1416
闪烁运动,
我们就可以找到行星。
08:21
we are able能够 to find planets行星.
173
489280
1656
我们就是用这种方法,
在银河系中探测到了
08:22
This is how we've我们已经 now been able能够
to detect检测 over 5,000 planets行星
174
490960
4176
5000多颗行星。
08:27
in our own拥有 Milky乳白色 Way,
175
495160
1216
08:28
and we know there are
many许多 more out there, like I mentioned提到.
176
496400
2856
而且就像我讲过的,
在银河系外还有很多行星。
所以当我们观察这些行星发出的光,
08:31
So when we look at the light
from these stars明星,
177
499280
2896
就像我说的,我们看到的不是行星本身,
08:34
what we see, like I said,
is not the planet行星 itself本身,
178
502200
3496
而是光亮的明暗,
08:37
but you actually其实 see
a dimming调光 of the light
179
505720
2056
我们可以记录它随时间的变化。
08:39
that we can record记录 in time.
180
507800
1656
08:41
So the light drops滴剂 as the planet行星
decreases降低 in front面前 of the star,
181
509480
3415
当行星绕到恒星前方,光亮就会变暗,
这就是你们之前看到的闪烁。
08:44
and that's that blinking闪烁
that you saw before.
182
512919
2417
所以我们不仅探测行星,
08:47
So not only do we detect检测 the planets行星
183
515360
1816
还透过不同的波长来观察星光。
08:49
but we can look at this light
in different不同 wavelengths波长.
184
517200
2815
我已经讲过,可以透过
紫外线来观察地球和火星。
08:52
So I mentioned提到 looking at the Earth地球
and Mars火星 in ultraviolet紫外线 light.
185
520039
4096
如果利用哈勃太空望远镜
观察凌日系外行星,
08:56
If we look at transiting过境 exoplanets系外行星
with the Hubble哈勃 Space空间 Telescope望远镜,
186
524159
3617
我们会发现,透过紫外线,
08:59
we find that in the ultraviolet紫外线,
187
527800
2096
当行星经过恒星前方时,
闪烁变得更明显,
09:01
you see much bigger blinking闪烁,
much less light from the star,
188
529920
3656
09:05
when the planet行星 is passing通过 in front面前.
189
533600
1776
星光也更暗。
我们认为,因为有一层厚厚的氧气
09:07
And we think this is because you have
an extended扩展 atmosphere大气层 of hydrogen
190
535400
3416
围绕着整个行星,
09:10
all around the planet行星
191
538840
1216
所以行星看上去更膨胀,
09:12
that's making制造 it look puffierpuffier
192
540080
1496
09:13
and thus从而 blocking闭塞
more of the light that you see.
193
541600
2320
于是挡住了更多光。
09:16
So using运用 this technique技术,
we've我们已经 actually其实 been able能够 to discover发现
194
544880
2896
运用这一技术,我们已经发现了
好几颗正在发生
大气逃逸的凌日系外行星。
09:19
a few少数 transiting过境 exoplanets系外行星
that are undergoing经历 atmospheric大气的 escape逃逸.
195
547800
4256
09:24
And these planets行星
can be called hot Jupiters木星,
196
552080
2816
在我们已发现的行星中,
09:26
for some of the ones那些 we've我们已经 found发现.
197
554920
1616
有一些可称为热木星。
这是因为这些行星
和木星一样,是气体行星,
09:28
And that's because
they're gas加油站 planets行星 like Jupiter木星,
198
556560
2576
但它们和自己的恒星距离相当近,
09:31
but they're so close to their star,
199
559160
1776
09:32
about a hundred times closer接近 than Jupiter木星.
200
560960
2256
大约是木星的百分之一。
而且由于有这些会逃逸的轻质气体,
09:35
And because there's all this
lightweight轻量级 gas加油站 that's ready准备 to escape逃逸,
201
563240
3456
以及来自恒星的热量,
09:38
and all this heating加热 from the star,
202
566720
1696
大气逃逸的发生是毫无疑问的。
09:40
you have completely全然 catastrophic灾难性的 rates利率
of atmospheric大气的 escape逃逸.
203
568440
3816
与地球每分钟失去400磅氢气不同,
09:44
So unlike不像 our 400 pounds英镑 per minute分钟
of hydrogen being存在 lost丢失 on Earth地球,
204
572280
4616
这些行星
09:48
for these planets行星,
205
576920
1256
每分钟失去13亿磅氢气。
09:50
you're losing失去 1.3 billion十亿
pounds英镑 of hydrogen every一切 minute分钟.
206
578200
4080
09:55
So you might威力 think, well,
does this make the planet行星 cease停止 to exist存在?
207
583320
4336
你可能会想,呃,
这会不会让行星不复存在?
而这正是人们观测
09:59
And this is a question
that people wondered想知道
208
587680
2016
太阳系时的疑问,
10:01
when they looked看着 at our solar太阳能 system系统,
209
589720
1816
因为距离太阳较近的行星为岩态,
10:03
because planets行星
closer接近 to the Sun太阳 are rocky岩石,
210
591560
2336
而距太阳远一些的行星体积更大,
气态程度更高。
10:05
and planets行星 further进一步 away
are bigger and more gaseous.
211
593920
2936
如果一个行星一开始像木星这样,
10:08
Could you have started开始
with something like Jupiter木星
212
596880
2376
离太阳又很近,
10:11
that was actually其实 close to the Sun太阳,
213
599280
1696
它的气体会不会全跑光?
10:13
and get rid摆脱 of all the gas加油站 in it?
214
601000
1616
10:14
We now think that if you start开始
with something like a hot Jupiter木星,
215
602640
3056
我们目前认为,如果一个行星
一开始像热木星一样,
那么它最终不会变得像水星或者地球。
10:17
you actually其实 can't end结束 up
with Mercury or the Earth地球.
216
605720
2816
10:20
But if you started开始 with something smaller,
217
608560
2176
但是一个体积更小的行星,
10:22
it's possible可能 that enough足够 gas加油站
would have gotten得到 away
218
610760
2776
是有可能因为气体逃逸太多
而受到明显影响的,
10:25
that it would have
significantly显著 impacted影响 it
219
613560
2136
最终,这个行星将变得
和一开始截然不同。
10:27
and left you with something very different不同
than what you started开始 with.
220
615720
3336
以上的内容都是泛泛而谈,
10:31
So all of this sounds声音 sort分类 of general一般,
221
619080
1896
我们想到的可能只是太阳系,
10:33
and we might威力 think about the solar太阳能 system系统,
222
621000
2536
但这和地球上的我们有什么关系?
10:35
but what does this have to do
with us here on Earth地球?
223
623560
2776
10:38
Well, in the far future未来,
224
626360
1776
其实,在遥远的未来,
10:40
the Sun太阳 is going to get brighter光明.
225
628160
2136
太阳会变得更亮。
如此一来,
10:42
And as that happens发生,
226
630320
1216
10:43
the heating加热 that we find from the Sun太阳
is going to become成为 very intense激烈.
227
631560
3320
太阳给我们带来的热量
就会变得非常强烈。
10:47
In the same相同 way that you see
gas加油站 streaming off from a hot Jupiter木星,
228
635600
4336
与我们所讲的热木星
流失气体的方式一样,
10:51
gas加油站 is going to stream off from the Earth地球.
229
639960
2336
地球也会流失气体。
10:54
And so what we can look forward前锋 to,
230
642320
2176
所以我们可以预料,
10:56
or at least最小 prepare准备 for,
231
644520
2056
或者至少有所准备的,
就是在遥远的未来,
10:58
is the fact事实 that in the far future未来,
232
646600
1816
11:00
the Earth地球 is going to look more like Mars火星.
233
648440
2776
地球将会看上去更像火星。
11:03
Our hydrogen, from water
that is broken破碎 down,
234
651240
2736
水分解产生的氢气
11:06
is going to escape逃逸
into space空间 more rapidly急速,
235
654000
2416
将以更快的速度逃逸到太空中,
11:08
and we're going to be left
with this dry, reddish planet行星.
236
656440
4080
留给我们一个干燥的红色星球。
不过别害怕,
最近几十亿年内还不会发生,
11:12
So don't fear恐惧, it's not
for a few少数 billion十亿 years年份,
237
660960
2496
11:15
so there's some time to prepare准备.
238
663480
1576
我们还有时间做准备。
11:17
(Laughter笑声)
239
665080
1056
(笑声)
11:18
But I wanted you
to be aware知道的 of what's going on,
240
666160
2816
但是我想让大家意识到
正在发生的事情:
11:21
not just in the future未来,
241
669000
1256
大气逃逸不只是在未来,
11:22
but atmospheric大气的 escape逃逸
is happening事件 as we speak说话.
242
670280
3216
而是此时此刻就在发生。
11:25
So there's a lot of amazing惊人 science科学
that you hear about happening事件 in space空间
243
673520
3496
关于太空和那些遥远的行星,
大家听说过很多
11:29
and planets行星 that are far away,
244
677040
1936
惊人的科学发现。
我们正在研究这些行星,
以便对那里的世界有更多了解。
11:31
and we are studying研究 these planets行星
to learn学习 about these worlds世界.
245
679000
3216
11:34
But as we learn学习 about Mars火星
or exoplanets系外行星 like hot Jupiters木星,
246
682240
4696
但在我们探索火星,或是
像热木星这样的系外行星的同时,
11:38
we find things like atmospheric大气的 escape逃逸
247
686960
3016
我们发现了诸如大气逃逸这样的现象,
从而大大增进了我们对地球的了解。
11:42
that tell us a lot more
about our planet行星 here on Earth地球.
248
690000
3736
11:45
So consider考虑 that the next下一个 time
you think that space空间 is far away.
249
693760
4056
如果你下次再觉得太空遥不可及,
不妨想想我今天的演讲。
11:49
Thank you.
250
697840
1216
谢谢大家。
(掌声)
11:51
(Applause掌声)
251
699080
3040
Translated by Yijing Li
Reviewed by Jiawei Ni

▲Back to top

ABOUT THE SPEAKER
Anjali Tripathi - Astrophysicist
Anjali Tripathi explores planets to uncover the processes that make and destroy them.

Why you should listen

Even though Anjali Tripathi worked on NASA's Mars rovers in high school, the California native never expected to become an astronomer. Unlike the earthquakes she researched early on, astronomy seemed unconnected from daily life. As she has since discovered, exploring distant planets has a lot to do with life itself -- including the fate of the air we breathe. Using some of the most powerful telescopes and supercomputers, Tripathi studies how seemingly permanent planets change over time. She has pioneered the characterization of planet-forming environments and developed computer simulations to trace the 3D structure of planet atmospheres that are shrinking due to evaporation.

A natural teacher, Tripathi makes complex science concepts relevant and easy to understand. She believes that everyone can understand science -- even rocket science. She has partnered with the Smithsonian, Teach for America and others to increase scientific literacy and spread enthusiasm for the subject. Her engaging and humorous talks feature real world connections and unusual props, including a fully functioning Mars Pathfinder rover or full-size solar car.

Tripathi earned degrees in physics and astronomy from M.I.T., the University of Cambridge and Harvard University. Recognized as a promising American leader with a commitment to public service, Tripathi is a 2016-17 White House Fellow.


More profile about the speaker
Anjali Tripathi | Speaker | TED.com

Data provided by TED.

This site was created in May 2015 and the last update was on January 12, 2020. It will no longer be updated.

We are currently creating a new site called "eng.lish.video" and would be grateful if you could access it.

If you have any questions or suggestions, please feel free to write comments in your language on the contact form.

Privacy Policy

Developer's Blog

Buy Me A Coffee