英语听力：自然百科 探索世界奥秘之Supermassive Black Holes(超大质量黑洞) Unit09

探索世界奥秘之Supermassive Black Holes(超大质量黑洞) Unit09

Four times a year, Ghez focuses the telescope on the stars of the very heart of our Milky¹ Way. She is looking for the telltale high speeds that reveal the presence of a black hole. The center of the Milky Way is so near and the Keck telescope so powerful Ghez is able to see closer into the center of the galaxy² than anyone has ever done before.

Here's an example of one of the images we got just last night. The seeing was, this was kind of a typical night, not the best night, not the worst night. Each one of these blobs here is a star, and what you see is each star is distorted, that's what the atmosphere does. It's like looking through a pond, like if you want to look at a penny at the bottom of a pond and the water's moving. It looks all distorted. It looks different every time you look, so this is one exposure and the next exposure looks like this.

By superimposing thousands of these pictures taken overnight, the computer can compensate³ for the atmosphere's distortion producing a detailed⁴ picture of the centre of the galaxy.

You can see the positions of the stars very accurately⁵. If we go in to the centre here, rescale it, we actually see that there are fainter stars towards the center of our field of view. And these stars are extremely important. It's the motion of these stars that reveal(s) the presence of the black hole.

Ghez has been following the motions of these stars for the last five years. If there was no black hole, they'd be moving very slowly, but she's discovered they are circling at speeds of over 1,000 kilometers a second.

These stars that we've been watching are two light weeks from this, from the center of our galaxy. So their motion, the fact they are going a thousand kilometers per second tells us that within two light weeks there is two million times the mass of the sun of matter there.

There's only one thing in the universe this dense⁶. Lying at the center of this necklace of spinning stars is a supermassive black hole. You can't see it, but it's there. The most destructive force in the universe is lurking⁷ at the heart of our very own galaxy, the Milky Way. The puzzle for cosmologists now is what effect it has on the galaxy around it.

seeing: Astronomy the quality of observed images as determined by atmospheric conditions

blob: an indeterminate roundish mass or shape

superimpose: place or lay (one thing) over another, typically so that both are evident

1 milky   

adj.牛奶的，多奶的；乳白色的

参考例句：

• Alexander always has milky coffee at lunchtime.亚历山大总是在午餐时喝掺奶的咖啡。
• I like a hot milky drink at bedtime.我喜欢睡前喝杯热奶饮料。

2 galaxy   

n.星系；银河系；一群(杰出或著名的人物)

参考例句：

• The earth is one of the planets in the Galaxy.地球是银河系中的星球之一。
• The company has a galaxy of talent.该公司拥有一批优秀的人才。

3 compensate   

vt.补偿，赔偿；酬报 vi.弥补；补偿；抵消

参考例句：

• She used her good looks to compensate her lack of intelligence. 她利用她漂亮的外表来弥补智力的不足。
• Nothing can compensate for the loss of one's health. 一个人失去了键康是不可弥补的。

4 detailed   

adj.详细的，详尽的，极注意细节的，完全的

参考例句：

• He had made a detailed study of the terrain.他对地形作了缜密的研究。
• A detailed list of our publications is available on request.我们的出版物有一份详细的目录备索。

5 accurately   

adv.准确地，精确地

参考例句：

• It is hard to hit the ball accurately.准确地击中球很难。
• Now scientists can forecast the weather accurately.现在科学家们能准确地预报天气。

6 dense   

a.密集的，稠密的，浓密的；密度大的

参考例句：

• The general ambushed his troops in the dense woods. 将军把部队埋伏在浓密的树林里。
• The path was completely covered by the dense foliage. 小路被树叶厚厚地盖了一层。

7 lurking   

潜在

参考例句：

• Why are you lurking around outside my house? 你在我房子外面鬼鬼祟祟的，想干什么？
• There is a suspicious man lurking in the shadows. 有一可疑的人躲在阴暗中。 来自《现代英汉综合大词典》