『新东方在线托福听力』为托福考生准备了ETS托福TPO/Official 55 Lec 3听力练习：What is the main purpose of the lecture?原文题目答案解析，TPO/Official 55 Lec 3听力原文范文音频翻译。

托福TPO/Official 55 Lec 3听力原文What is the main purpose of the lecture?【新东方在线】

旁白：听天文学课上的部分演讲。教授正在讨论极光。

NARRATOR:Listen to part of a lecture in an astronomy class. The professor is discussing auroras.

极光是指北极和南极附近夜空中的明亮色彩的光线，在北半球，它被称为北极光，在南半球，它被称为南极光。

The aurora refers to the rays of bright colors in the night sky near the North and South Poles—in the Northern Hemisphere it’s called the aurora borealis and in the Southern Hemisphere it’s called the aurora australis.

你可能已经看过它的照片了，它很漂亮。

You’ve probably seen pictures of it; it’s quite beautiful.

人们花了几个世纪的时间才弄清楚夜空中这些美丽色彩的背后是什么。

It took centuries to figure out what’s behind these beautiful colors in the night skies.

在 1700 年代初期，科学家们提出在北极和南极之间存在电流，如果电流受到干扰，就会形成极光。

In the early 1700s, scientists proposed that there was an electric current that stretched between the North and South Poles, and that if this electric current was disturbed, an aurora would form.

其他人推测，这种现象是由北极的冰川和雪折射的光线引起的。

Others postulated that the phenomenon was caused by light that refracted off glaciers and snow in the Arctic.

然后在 1800 年代，对地球磁场的科学兴趣、对地球磁场的奇怪变化的观察导致观察到最大的磁场干扰与剧烈的极光同时发生，也与最强烈的太阳黑子活动的时间相吻合。

Then, in the 1800s, scientific interest in Earth’s magnetic field—in strange variations in Earth’s magnetic field—led to the observation that the biggest magnetic disturbances coincided with dramatic auroras, and also with the timing of the most intense sunspot activity.

太阳黑子在几个世纪前首次被观察到，即太阳表面的暂时性黑点。它们是在太阳表面移动的气态、高磁性区域。

Sunspots were first observed centuries earlier… temporary, dark spots on the face of the Sun… they’re gaseous, highly magnetic regions that move across the Sun’s surface.

太阳黑子周期每十一年达到一次高峰，极光周期也是如此。他们一起达到顶峰。

Sunspot cycles are at their height every eleven years, and so are aurora cycles. They peak together.

到了 20 世纪初，人们发现地球的磁场不断受到来自太阳的带电粒子的轰击。我们称之为太阳风。

By the early twentieth century, it was found that Earth’s magnetic field is constantly being bombarded by charged particles streaming from the Sun—we call it solar wind.

我需要告诉你什么时候太阳风特别强烈吗？

And do I need to tell you when the solar wind is especially strong?

是的，每十一年，太阳黑子的磁活动达到顶峰。

Yep, every eleven years, when the magnetic activity of sunspots is peaking.

带电粒子与地球磁场相互作用，它们被拉向北极和南极。

The charged particles interact with Earth’s magnetic field, and they’re pulled toward the North and South Poles.

其中一些进入了我们的高层大气，在那里它们与氧原子和氮原子发生碰撞。

Some of them make it into our upper atmosphere, where they collide with atoms—with oxygen and nitrogen atoms.

这种碰撞导致原子发光，不同类型的原子发出不同的颜色。

This collision causes the atoms to light up, to glow… different types of atoms glowing different colors.

这就是我们看到极光时正在发生的事情。

And this is what’s happening when we’re seeing an aurora.

现在，让我们跳到 1970 年代初期，使用一种叫做日冕仪的设备有了一个发现。

Now let’s jump ahead to the early 1970s and a discovery made using a device called a coronagraph.

日冕仪附在望远镜上，就像一个挡住太阳的圆盘，当你通过望远镜观察时，它会产生所谓的人造日食。

A coronagraph attaches to a telescope and acts like a disk that blocks out the Sun… it creates an artificial solar eclipse, you could say, when you’re looking through the telescope.

这使得太阳的日冕或外层大气更容易观察。

This makes the Sun’s corona, or outer atmosphere, much easier to observe.

好，确实每当发生日全食时，你们都可以看到日冕，即围绕太阳的外部白色圆圈。

Now it’s true that whenever there’s a total eclipse of the Sun you can see the corona… that outer white circle surrounding the Sun.

但是日全食会持续多久呢？不到十分钟？它们可能每年发生一次。

But how long does a total solar eclipse last? … Less than ten minutes? And they occur maybe once a year.

使用日冕仪，你们可以随时连续观察日冕。

With a coronagraph, you can observe the corona continuously, anytime you want.

在 1970 年代初期，我们使用安装在轨道卫星上的日冕仪，目睹了所谓的日冕物质抛射，简称CME。

And during the early 1970s, using a coronagraph mounted on an orbiting satellite, we witnessed what are called coronal mass ejections—or CMEs for short.

那么，日冕物质抛射，那些是什么？

So coronal mass ejections; what are those?

嗯，它们是巨大的磁化气体云，在巨大的大气风暴期间从太阳抛出。

Well, they’re huge, magnetized gas clouds that’re thrown from the Sun during a big atmospheric storm.

它们在几个小时内从太阳中喷发。

They erupt from the Sun over the course of several hours.

这些巨大的云是由数十亿吨以难以置信的高速冲向地球的带电粒子组成的。

These huge clouds are made of billions of tons of those charged particles—that rush toward the Earth at incredibly high speeds.

这个质量在短短几个小时到几天内到达我们地球的磁场。

This mass reaches our planet’s magnetic field in anywhere from just several hours to a few days.

因此，我们发现在CME期间，由于太阳大量喷射粒子，极光特别强烈。

So we found that during CMEs—with their enormous ejections of particles from the Sun—auroras are particularly intense.

现在，正如我们所说，我们可以预测峰值和太阳黑子活动，但到目前为止，我们还不能对CME做同样的预测。

Now, as we’ve said, we can predict peaks in sunspot activity, but so far we can’t say the same for CMEs.

我们不知道它们何时会发生或它们会有多大。

We don’t know when they’ll occur or how large they’ll be.

但是知道这一点有什么好处呢？

But what would be the advantage in knowing that?

嗯，纵观历史，我们已经注意到极光强度和技术问题之间的相关性，即极光的一些干扰性——首先是指南针走歪，然后当我们发明了电报系统，电报系统受到了影响；然后是电话系统和短波无线电系统；如今，被影响的甚至是整个发电站。

Well, throughout history, we’ve noticed correlations between aurora intensity and technical problems, uh, disruptions—first with compasses going awry, then when we developed telegraph systems they were affected, and then telephone systems, and shortwave radio systems... today even whole electrical power stations.

例如，1989年，太阳耀斑引发了一场非常强烈的磁暴，导致加拿大魁北克省电力中断了12小时。

For example, in 1989 there was a really intense magnetic storm initiated by a flare-up on the Sun, and it caused electricity to go out for twelve hours in Quebec, Canada.

According to the professor, what theories were proposed in the 1700s to account for the occurrence of auroras? [Click on 2 answers.]

Why does the professor mention the duration of solar eclipses?

What point does the professor make when he talks about disruptions to technology?

NARRATORListen to part of a lecture in an astronomy class. The professor is discussing auroras.MALE PROFESSOR OK. The aurora. The aurora refers to the rays of bright colors in the night sky near the North and South Poles—in the Northern Hemisphere it’s called the aurora borealis and in the Southern Hemisphere it’s called the aurora australis. You’ve probably seen pictures of it; it’s quite beautiful.It took centuries to figure out what’s behind these beautiful colors in the night skies. In the early 1700s, scientists proposed that there was an electric current that stretched between the North and South Poles, and that if this electric current was disturbed, an aurora would form. Others postulated that the phenomenon was caused by light that refracted off glaciers and snow in the Arctic.Then, in the 1800s, scientific interest in Earth’s magnetic field—in strange variations in Earth’s magnetic field—led to the observation that the biggest magnetic disturbances coincided with dramatic auroras, and also with the timing of the most intense sunspot activity. Sunspots were first observed centuries earlier… temporary, dark spots on the face of the Sun… they’re gaseous, highly magnetic regions that move across the Sun’s surface. Sunspot cycles are at their height every eleven years, and so are aurora cycles. They peak together.By the early twentieth century, it was found that Earth’s magnetic field is constantly being bombarded by charged particlesstreaming from the Sun—we call it solar wind. And do I need to tell you when the solar wind is especially strong? Yep,every eleven years, when the magnetic activity of sunspots is peaking.The charged particles interact with Earth’s magnetic field, and they’re pulled toward the North and South Poles. Some of them make it into our upper atmosphere, where they collide with atoms—with oxygen and nitrogen atoms. This collision causes the atoms to light up, to glow… different types of atoms glowing different colors. And this is what’s happening when we’re seeing an aurora.Now let’s jump ahead to the early 1970s and a discovery made using a device called a coronagraph.A coronagraph attaches to a telescope and acts like a disk that blocks out the Sun… it creates an artificial solar eclipse, you could say, when you’re looking through the telescope. This makes the Sun’s corona, or outer atmosphere, much easier to observe. Now it’s true that whenever there’s a total eclipse of the Sun you can see the corona… that outer white circle surrounding the Sun. But how long does a total solar eclipse last?…Less than ten minutes? And they occur may be once a year. With a coronagraph, you can observe the corona continuously, anytime you want. And during the early 1970s, using a coronagraph mounted on an orbiting satellite, we witnessed what are called coronal mass ejections—or CMEs forshort.So coronal mass ejections; what are those? Well, they’re huge, magnetized gas clouds that’re thrown from the Sun during a big atmospheric storm. They erupt from the Sun over the course of several hours. These huge clouds are made of billions of tons of those charged particles—that rush toward the Earth at incredibly high speeds. This mass reaches our planet’s magnetic field in anywhere from just several hours to a few days.So we found that during CMEs—with their enormous ejections of particles from the Sun—auroras are particularly intense.Now, as we’ve said, we can predict peaks in sunspot activity, but so far we can’t say the same for CMEs. We don’t know when they’ll occur or how large they’ll be.But what would be the advantage in knowing that? Well, throughout history, we’ve noticed correlations between aurora intensity and technical problems, uh, disruptions—first with compasses going awry, then when we developed telegraph systems they were affected, and then telephone systems, and shortwave radio systems... today even whole electrical power stations. For example, in 1989 there was a really intense magnetic storm initiated by a flare-up on the Sun, and it caused electricity to go out for twelve hours in Quebec, Canada.

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