『新东方在线托福听力』为托福考生准备了ETS托福TPO/Official 19 Lec 2听力练习：What is the lecture mainly about?原文题目答案解析，TPO/Official 19 Lec 2听力原文范文音频翻译。

托福TPO/Official 19 Lec 2听力原文What is the lecture mainly about?-新东方托福官方网校手机版

Narrator: Listen to part of a lecture in an astronomy class.

教授：嗯，你们中有多少人注意过银河系，观测过它的天象？

Professor: So how many of you have seen the Milky Way, the Milky Galaxy in the sky?

男学生：是的，我曾露营的时候观测过，当时天上没有月亮，四周很暗。

Male Student: Yeah, I was camping, and there was no moon that night, it was super dark.

教授：还有别的同学吗？嗯，没有多少同学看过。

银河系是我们地球安身的地方，但大多数同学们却从来没有注意过，这难道不奇怪吗？

Isn't that strange that the Milky Way is the galaxy that the planet earth is in, and most of us have never seen it?

嗯，既然如此，问题在哪儿呢？

教授：是的，特别是没有加灯罩的路灯，它们的光是漫射的。

Professor: Yes, Especially unshielded street light, you know, ones that aren't pointed downward.

现在，我给大家讲一件比较讽刺的事情，和观测楼隔得不远的、我们现在所在的这栋天文中心，就安装了无罩灯。

Now, here's an irony, the building we are in now, the astronomy building not far from our observatory, has unshielded lights.

男学生：所以这个问题其实特别普遍。

Male Student: So the problem is pretty widespread.

教授：这个问题基本上超出了控制范围，我的意思是，对于在城市中观测天空来讲。

Professor: It is basically beyond control, as far as expecting to view the night sky anywhere near city, I mean.

并且在市区里我从来没有看到过银河系的模样，而且可能我永远也看不到。

And I have never seen the Milky Way within city limits, and I probably never will.

所以，发展、进步是要付出代价的，对吧？

那么，我们再想想，除了光污染这一种科技进步导致的天文观测不便之外。

But let's think beyond light pollution, that's only one kind of a technological advance that has interfered with astronomical research.

有同学能想到别的吗？没有吗？

好吧，我来给大家一些提示吧，过去70年里，我们不只是靠肉眼观测天空来获得天文信息，我们还用无线电技术，它使得我们可以研究天空中的各种波段。

Ok, let's look at it this way, we don't only gain information by looking at the stars, for the past 70 years or so, we have also used radio astronomy, which lets us study radio waves from the sky.

Male Student: How can you observe radio waves?

我的意思是，怎样利用波段来解读行星相关的信息？

I mean, tell anything about the stars from that.

教授：嗯，在光电天文学领域中，我们的观测工具是望远镜，通过可见光波来研究星体。

Professor: Well, in optical astronomy, using a telescope and observing the stars that way, we rely on visible light waves.

我们在地球上接受到的图像，实际上是来自其它星球的电磁波。

What we are seeing from earth is actually electromagnetic radiation that's coming from stars.

And just one part of it is visible light.

当光子和光波击打在我们大气层的水滴、氧气和氮气分子上时。

When photons and light waves hit objects in our atmosphere, water droplets, oxygen and nitrogen molecules, dust particles and so on,

它们就被点亮了，而这些东西同时也可能会被我们的街灯、月光等不明光源点亮。

these objects are illuminated, they are lit up, and those things are also being lit by all our streetlights, by the moon, all these ambient light.

这样的话，当可见光波从这些分子上反射出去的时候，它就向四周分散了。

And on top of that, when that visible radiation bounces off those molecules, it scatters in all directions.

这样一来，从其它星球发射出来的光——即使它们的距离和地球很近同在银河系——都将无一幸免。

And well, light from stars, even nearby in our own galaxy, doesn't stand a chance against that.

事实上，经地球附近物体散射的光源亮度，要比来自形体光源的光亮度强得多。

Basically the light bouncing off all these objects close to earth is brighter than what's coming from the stars.

而无线电波则是我们看不到的电磁波。

Now, radio waves are electromagnetic radiation that we can't see.

几乎宇宙中的所有天体都会发射电磁波，无论是近星域还是遥远星域的物体，它们随时随地都在发射电磁波。

Nearly all astronomical objects in space emit radio waves, whether nearby stars, objects in faraway galaxies, they all give off radio waves.

而且这些波与可见光不同之处在于，它们可以相对容易地穿透各种气障和尘障，穿过我们的大气层。

And unlike visible light waves, these radio waves can get through the various gases and dusts in space, and through our own earth's atmosphere comparatively easily.

女学生：这样的话，我们会放弃光学观测手段，转而使用无线电观测手段。

Female Student: Ok, then we might as well give up on optical astronomy and go with radio astronomy.

教授：嗯，情况是，我们当然不能只在后院立一个射电望远镜然后就依靠它观察星空。

Professor: Well, the thing is, with the radio astronomy, you can't just set up a telescope in your backyard and observe stars.

这样做的一个问题是，从遥远星体上发射过来的电波，即便它们能够穿透大气层，依然非常的微弱。

One problem is that radio waves from these far away objects, even though they can get through, are extremely faint.

所以我们还需要一种专门设计用于接收这些电波的无线电望远镜，并且根据我们接受的信息，通过电脑模拟图像。

So we need to use radio telescopes, specially designed to receive these waves and then, well, we can use computers to create pictures based on the information we receive.

教授：如果你知道卫星接收盘的接收信号的原理的话，无线电望远镜的工作原理和它差不多。

Professor: Well, it is kind of like the same way a satellite dish receives its signal, if you are familiar with that.

但无线电望远镜的接收器常常建立在一起的，相当于组成一个更大型的望远镜以增强其无线电波接收能力。

But radio telescopes are sometimes grouped together, is the same effect as having one big telescope to increase radio wave gathering power.

它们还使用了电子设备，相当复杂。

And they use electronics, quite sophisticated.

这些仪器的运作的确了不起，但现在我们来看我们能从中学到什么。

Yeah, it is neat how they do it, but for now why don't we just stick with what we can learn from it.

这项创新使得我们获得了许多重大的发现，特别是关于那些在太空中只发射无线电波而不发射光的物体的。

Some very important discoveries have been made by this technology, especially you consider that some objects in space give off radio waves but don't emit any light.

我们曾经在研究这一类天体时很不顺利，因为光学镜不能进行太多有效的研究。

We have trouble discovering those sorts of bodies, much less studying them using just optical telescopes.

女学生：嗯，如果无线电波真的能够穿透宇宙空间的话，您之前所说的弊端，到底是指什么呢？

Female Student: Well, if the radio waves are so good at getting through the universe, what's the problem?

教授：它的答案与这个问题是一样的。

为什么人们在飞机降落的时候要关闭手机登电子设备呢？

How come people have to turn off their cell phones and all our electronic devices when an airplane is about to take off?

男学生：因为电话干扰了飞机和机场的无线电通信，是吗？

Male Student: The phones interfere with the radio communication at the airport, right?

女学生：这样说来，地球上的无线电信号干扰了宇宙传来的电波？

Female Student: Oh, so our radio waves here on earth interfere with the waves from space?

教授：对的，电台、手机、电视台、无限遥控等你们所知的无线电设备。

Professor: Yes, signal from radios, cell phones, TV stations, remote controls, you name it.

我们对此的考虑不如光污染多。

We don't think about that as often as we think about light pollution.

但这些电子仪器同样污染了天空，只是方式不一样罢了。

But all those electrical gadgets pollute the skies, just in a different way.

What is the professor's attitude about light pollution in cities?

According to the professor, why are radio waves particularly useful for astronomical observations?

What does the professor imply is an advantage of optical astronomy over radio astronomy?

According to the professor, why do radio astronomers sometimes have difficulty studying very distant objects?

What does the professor mean when he says this:

Narrator 
Listen to part of a lecture in an astronomy class. 
Professor 
So how many of you have seen the Milky Way, the Milky Galaxy in the sky? You, you have? 
Student 
Yeah, I was camping, and there was no moon that night, it was super dark. 
Professor 
Anybody else? Not too many. Isn’t that strange that the Milky Way is the galaxy that the planet earth is in, and most of us have never seen it? Now, what’s the problem here? 
Student 
Light pollution, right? From street lights and stuff ... 
Professor 
Yes, Especially unshielded street light, you know, ones that aren’t pointed downward. Now, here’s an irony, the building we are in now, the astronomy building not far from our observatory, has unshielded lights. 
Student 
So the problem is pretty widespread. 
Professor 
It is basically beyond control, as far as expecting to view the night sky anywhere near city, I mean. I have lived around here my whole life. And I have never seen the Milky Way within city limits, and I probably never will. There is a price for progress, eh? But let’s think beyond light pollution, that’s only one kind of a technological advance that has interfered with astronomical research. 
Can anyone think of another? No? Ok, let’s look at it this way, we don’t only gain information by looking at the stars, for the past 70 years or so, we have also used radio astronomy, which lets us study radio waves from the sky. 
Student 
How can you observe radio waves? I mean, tell anything about the stars from that. 
Professor 
Anybody else? Not too many. Isn’t that strange that the Milky Way is the galaxy that the planet earth is in, and most of us have never seen it? Now, what’s the problem here? 
Student 
Light pollution, right? From street lights and stuff ... 
Professor 
Yes, Especially unshielded street light, you know, ones that aren’t pointed downward. Now, here’s an irony, the building we are in now, the astronomy building not far from our observatory, has unshielded lights. 
Student 
So the problem is pretty widespread. 
Professor 
It is basically beyond control, as far as expecting to view the night sky anywhere near city, I mean. I have lived around here my whole life. And I have never seen the Milky Way within city limits, and I probably never will. There is a price for progress, eh? But let’s think beyond light pollution, that’s only one kind of a technological advance that has interfered with astronomical research. 
Can anyone think of another? No? Ok, let’s look at it this way, we don’t only gain information by looking at the stars, for the past 70 years or so, we have also used radio astronomy, which lets us study radio waves from the sky. 
Professor 
Well, in optical astronomy, using a telescope and observing the stars that way, we rely on visible light waves. What we are seeing from earth is actually electromagnetic radiation that’s coming from stars. And just one part of it is visible light. But there are problems with that. When photons and light waves hit objects in our atmosphere, water droplets, oxygen and nitrogen molecules, dust particles and so on. These objects are illuminated, they are lit up, and those things are also being lit by all our street lights, by the moon, all these ambient light. And on top of that, when that visible radiation bounces off those molecules, it scatters in all directions. And well, light from stars, even nearby in our own galaxy, doesn’t stand a chance against that. Basically the light bouncing off all these objects close to earth is brighter than what’s coming from the stars. 
Now, radio waves are electromagnetic radiation that we can’t see. Nearly all astronomical objects in space emit radio waves, whether nearby stars, objects in faraway galaxies, they all give off radio waves. And unlike visible light waves, these radio waves can get through the various gases and dusts in space, and through our own earth’s atmosphere comparatively easily. 
Student 
Ok, then we might as well give up on optical astronomy and go with radio astronomy. 
Professor 
Well, the thing is, with the radio astronomy, you can’t just set up a telescope in your backyard and observe stars. 
One problem is that radio waves from these far away objects, even though they can get through, are extremely faint. So we need to use radio telescopes, specially designed to receive these waves and then, well, we can use computers to create pictures based on the information we receive. 
Student 
That sounds cool. So, how do they do that? 
Professor 
Well, it is kind of like the same way a satellite dish receives its signal, if you are familiar with that. But radio telescopes are sometimes grouped together, is the same effect as having one big telescope to increase radio wave gathering power. And they use electronics, quite sophisticated. Yeah, it is neat how they do it, but for now why don’t we just stick with what we can learn from it. Some very important discoveries have been made by this technology, especially you consider that some objects in space give off radio waves but don’t emit any light. We have trouble discovering those sorts of bodies, much less studying them using just optical telescopes. 
Student 
Well, If the radio waves are so good at getting through the universe, what’s the problem? 
Professor 
Well, answer this. How come people have to turn off their cell phones and all our electronic devices when an 
airplane is about to take off? 
Student 
The phones interfere with the radio communication at the airport, right? 
Student 
Oh, so our radio waves here on earth interfere with the waves from space? 
Professor 
Yes, signal from radios, cell phones, TV stations, remote controls, you name it. All these things cause interference. 
We don’t think about that as often as we think about light pollution. But all those electrical gauges pollute the skies, just in a different way. 
Student 
That sounds cool. So, how do they do that? 
Professor 
Well, it is kind of like the same way a satellite dish receives its signal, if you are familiar with that. But radio telescopes are sometimes grouped together, is the same effect as having one big telescope to increase radio wave gathering power. And they use electronics, quite sophisticated. Yeah, it is neat how they do it, but for now why don’t we just stick with what we can learn from it. Some very important discoveries have been made by this technology, especially you consider that some objects in space give off radio waves but don’t emit any light. We have trouble discovering those sorts of bodies, much less studying them using just optical telescopes.