英语听力：自然百科 探索世界奥秘之Supermassive Black Holes(超大质量黑洞) Unit05

探索世界奥秘之Supermassive Black Holes(超大质量黑洞) Unit05

By measuring how fast these stars were moving, he could prove if there really was a black hole at the center of an active galaxy¹.

I picked a galaxy nearby which is called NGC 1068, an active galaxy, which meant that it probably had a supermassive black hole in it, at least, that's what we wanted to prove.

To be certain that the stars were moving unnaturally² fast in NGC 1068, Dresslar wanted to compare them with stars in a normal galaxy without a black hole. Stars circling around a weak center of gravity would move at half the speed. So for this comparison, he chose the very ordinary galaxy next door to us, Andromeda(仙女座), with a quiet, inactive center like our own.

To measure the speed of the stars in these two very different galaxies³, Dresslar used an instrument called a spectroscope. This looks at the changing pattern of light coming from stars as they rotate around the galaxy core. The spectroscope shows the center of the galaxy as a white band and the movement of stars around the core is traced by a dark, vertical⁴ line. If the stars of the galaxy's center are circling slowly, then the dark band would show hardly any change, but if they are traveling at great speed, whizzing towards and away from us either side of a supermassive black hole, then the dark band should show a sudden shift across the center of the galaxy.

I would expect to see some rather rapid change in this dark line so that there'd be a very big change in the speed from one side of the galaxy to the other, very suddenly, right over the center and that would show that the stars were moving very rapidly in the center of the galaxy because of the influence of the great mass in the center, the supermassive black hole.

Over the next a few nights, Dresslar measured the speed of the stars in NGC 1068 and in Andromeda.

spectroscope: an apparatus for producing and recording spectra for examination

whiz: move quickly through the air with a whistling or whooshing sound

1 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。

2 unnaturally   

adv.违反习俗地；不自然地；勉强地；不近人情地

参考例句：

• Her voice sounded unnaturally loud. 她的嗓音很响亮，但是有点反常。 来自《简明英汉词典》
• Her eyes were unnaturally bright. 她的眼睛亮得不自然。 来自《简明英汉词典》

3 galaxies   

星系( galaxy的名词复数 )； 银河系； 一群（杰出或著名的人物）

参考例句：

• Quasars are the highly energetic cores of distant galaxies. 类星体是遥远星系的极为活跃的核心体。
• We still don't know how many galaxies there are in the universe. 我们还不知道宇宙中有多少个星系。

4 vertical   

adj.垂直的，顶点的，纵向的；n.垂直物，垂直的位置

参考例句：

• The northern side of the mountain is almost vertical.这座山的北坡几乎是垂直的。
• Vertical air motions are not measured by this system.垂直气流的运动不用这种系统来测量。