PBS高端访谈:科学家发现宜居新行星 离地球4光年

 　　HARI SREENIVASAN: Time now for our weekly segment on science called the Leading Edge, and the discovery of another possible Earth-like planet that's grabbing worldwide attention today.

　　It is true, scientists have previously¹ said they believe there are other planets outside our solar system that resemble Earth in size and may have liquid water. But this latest finding is the closest planet yet found. Yes, it's four light years from Earth, just a mere² 25 trillion miles away. But travel there may be possible by the end of the century, maybe not for me and you.

　　The planet is called Proxima b, circling a small star called Proxima Centauri. As shown in this animation³, it's thought to be about 1.3 times the mass of Earth, probably rocky like the Earth, and possibly warm enough for liquid water.

　　Let's learn more now from our science correspondent and resident space expert, Miles O'Brien.

　　Miles, first of all, why are they so excited about this? We have heard about the planets and this kind of Goldilocks, not too hot, not too cold, places before?

　　MILES O'BRIEN: Location, location, location, Hari.

　　We're talking now of about more than 3,000 planets total, exoplanets in the catalogue, and growing by the minute, but this is the closest one that's been discovered. And that is what has scientists quite interested.

　　Four light years is, in astronomical⁴ terms, a trip to the convenience store. And so the idea that there might be something somewhat within the realm of attainable⁵ if we come up with some really cool rocket propulsion ideas gets people thinking.

　　HARI SREENIVASAN: How do we know it is what it is? We can't see it from our eyes. There's telescopes that see things, but they didn't really get a picture of this planet.

　　MILES O'BRIEN: It's indirect.

　　Imagine driving down a darkened highway and a car coming at with its high beams on. You don't know anything about that car, do you? But there are some ways to kind of figure this out using some interesting technology.

　　In this case, what they used was the slight wobble that occurs as these two bodies interact with each other. As the planet orbits around, the star itself moves ever so slightly. That's enough to infer that its presence is there.

　　There are a few other ways to do it. You can actually detect the slight diminishment of light as a planet passes in front of a star and infer that its presence is there that way. That's how the Kepler space telescope has done its work so well over the years for NASA.

　　科学家发现宜居新行星 离地球4光年

　　HARI SREENIVASAN: So, tell us what scientists think they know about this planet in relation to the Earth.

　　MILES O'BRIEN: Well, I don't think we want to live there, Hari.

　　It's 11 days around its star, so an 11-day year. It is tidily locked, which means there is a light side always and a dark side always. So I suppose the real estate on the light side might be better. I don't know. If you're a night owl⁶, maybe you want to go to the other side.

　　It's very close to its star, but the star itself is a brown dwarf⁷. It's a pretty wimpy⁸ star. And so it can be closer and be in what scientists call the Goldilocks zone, the just-right zone where the temperatures are just right for water to exist in liquid form.

　　And here's the thing to remember. Wherever we look on this planet, no matter where we go, deep down in the ocean, in acid springs in Yellowstone, if there is liquid water, we find life.

　　HARI SREENIVASAN: And so there could possibly be — even under this star's light, there could be something maybe subterranean⁹, life underground, or whatever constitutes ground on that planet?

　　MILES O'BRIEN: It will take a while, maybe a decade, to kind of figure this all out, because, again, we haven't seen it directly.

　　And — but this is something that has scientists very intrigued¹⁰. And as technology improves — and NASA will be launching another spacecraft coming up in a year or so called TESS that will be a little more powerful and will be looking a little bit closer to us than its predecessor¹¹, Kepler.

　　Possibly, it will solve some of those questions for us and determine if, in fact, there might be life that close to us.

　　HARI SREENIVASAN: And so there are some projects kind of at least planned on getting very, very small sort of sensors¹² or objects out farther and farther into space. How could we ever, in our lifetimes, maybe not in our lifetime, our children's lifetimes, reach this to get a look at it?

　　MILES O'BRIEN: Well, we have to think about some new ways of doing propulsion in space.

　　Some sort of nuclear option is what we're talking about here. Once you get into space, if you can have steady propulsion that never stops, fueled by some sort of nuclear reaction, you continue to accelerate, because there's no friction¹³ in space, of course.

　　And so ultimately you can develop some real speed. And, potentially, some ideas on the drawing board could make that trip of four light years something on the order of a century or maybe a little less.

　　Right now, if you wanted to, say, launch the space shuttle, not that it could go there, but if you wanted to, just for point of reference, it would be more than 100,000 years to get there. Voyager, for example, just leaving our solar system, if you aimed it at this newly discovered planet, voyager would take about 70,000 years to get there.

　　So, that gives you an idea, where it's not just billions and billions. We're talking trillions and trillions here.

　　HARI SREENIVASAN: And to get a photo back from there would take several years too.

　　MILES O'BRIEN: Well, you know, that's just it.

　　The speed of light, four-and-a-half light years away, so it's four-and-a-half years to get any transmission back and forth¹⁴. So it would be really hard to engage in any sort of jokes with the people who might live on this planet.

　　You know, comedy is timing¹⁵, of course.

　　HARI SREENIVASAN: Right.

　　Miles O'Brien joining us from Boston, thanks so much.

　　MILES O'BRIEN: You're welcome.

1 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

2 mere   

adj.纯粹的；仅仅，只不过

参考例句：

• That is a mere repetition of what you said before.那不过是重复了你以前讲的话。
• It's a mere waste of time waiting any longer.再等下去纯粹是浪费时间。

3 animation   

n.活泼，兴奋，卡通片／动画片的制作

参考例句：

• They are full of animation as they talked about their childhood.当他们谈及童年的往事时都非常兴奋。
• The animation of China made a great progress.中国的卡通片制作取得很大发展。

4 astronomical   

adj.天文学的，（数字）极大的

参考例句：

• He was an expert on ancient Chinese astronomical literature.他是研究中国古代天文学文献的专家。
• Houses in the village are selling for astronomical prices.乡村的房价正在飙升。

5 attainable   

a.可达到的，可获得的

参考例句：

• They set the limits of performance attainable. 它们确定着可达到的运行限度。
• If objectives are to be meaningful to people, they must be clear, attainable, actionable, and verifiable. 如果目标对人们是具有意义的，则目标必须是清晰的，能达到的，可以行动的，以及可供检验的。

6 owl   

n.猫头鹰，枭

参考例句：

• Her new glasses make her look like an owl.她的新眼镜让她看上去像只猫头鹰。
• I'm a night owl and seldom go to bed until after midnight.我睡得很晚，经常半夜后才睡觉。

7 dwarf   

n.矮子，侏儒，矮小的动植物；vt.使…矮小

参考例句：

• The dwarf's long arms were not proportional to his height.那侏儒的长臂与他的身高不成比例。
• The dwarf shrugged his shoulders and shook his head. 矮子耸耸肩膀，摇摇头。

8 wimpy   

adj.懦弱的，无用的，哭哭啼啼的

参考例句：

• I'd rather have a wimpy kid than a dead one, you know? 你知道么？我宁可要一个懦弱的孩子，也不想要一个死的。 来自互联网
• I hate wimpy drinker. 我讨厌酒量差的人。 来自互联网

9 subterranean   

adj.地下的，地表下的

参考例句：

• London has 9 miles of such subterranean passages.伦敦像这样的地下通道有9英里长。
• We wandered through subterranean passages.我们漫游地下通道。

10 intrigued   

adj.好奇的，被迷住了的v.搞阴谋诡计(intrigue的过去式)；激起…的兴趣或好奇心；“intrigue”的过去式和过去分词

参考例句：

• You've really intrigued me—tell me more! 你说的真有意思—再给我讲一些吧！
• He was intrigued by her story. 他被她的故事迷住了。

11 predecessor   

n.前辈，前任

参考例句：

• It will share the fate of its predecessor.它将遭受与前者同样的命运。
• The new ambassador is more mature than his predecessor.新大使比他的前任更成熟一些。

12 sensors   

n.传感器，灵敏元件( sensor的名词复数 )

参考例句：

• There were more than 2000 sensors here. 这里装有两千多个灵敏元件。 来自《简明英汉词典》
• Significant changes have been noted where sensors were exposed to trichloride. 当传感器暴露在三氯化物中时，有很大变化。 来自辞典例句

13 friction   

n.摩擦，摩擦力

参考例句：

• When Joan returned to work,the friction between them increased.琼回来工作后，他们之间的摩擦加剧了。
• Friction acts on moving bodies and brings them to a stop.摩擦力作用于运动着的物体，并使其停止。

14 forth   

adv.向前；向外，往外

参考例句：

• The wind moved the trees gently back and forth.风吹得树轻轻地来回摇晃。
• He gave forth a series of works in rapid succession.他很快连续发表了一系列的作品。

15 timing   

n.时间安排，时间选择

参考例句：

• The timing of the meeting is not convenient.会议的时间安排不合适。
• The timing of our statement is very opportune.我们发表声明选择的时机很恰当。