VOA慢速英语 EXPLORATIONS - Edwin Hubble Changed Our Ideas About

ANNOUNCER:

EXPLORATIONS -- a program in Special English by the Voice of America.

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Today, Richard Rael and Tony Riggs tell the story of American astronomer¹ Edwin Hubble. He changed our ideas about the universe and how it developed.

Edwin Hubble made his most important discoveries in the nineteen twenties. Today, other astronomers² continue the work he began. Many of them are using the Hubble space telescope that is named after him.

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VOICE TWO:
　
Edwin Hubble

Edwin Powell Hubble was born in eighteen eighty-nine in Marshfield, Missouri. He spent his early years in the state of Kentucky. Then he moved with his family to Chicago, Illinois. He attended the University of Chicago. He studied mathematics and astronomy³.

Hubble was a good student. He was a good athlete, too. He was a member of the University of Chicago championship basketball team in nineteen-oh-nine. He also was an excellent boxer⁴. Several people urged him to train for the world heavyweight boxing championship after college. Instead, he decided⁵ to continue his studies. He went to Queen's College at Oxford⁶, England.

At Oxford, Hubble studied law. He was interested in British Common Law, because his family had come to America from England many years before. He spent three years at Oxford.

In nineteen thirteen, Hubble returned to the United States. He opened a law office in Louisville, Kentucky. After a short time, however, he decided he did not want to be a lawyer. He returned to the University of Chicago. There, once again, he studied astronomy.

VOICE ONE:

Hubble watched the night sky with instruments at the university's Yerkes Observatory⁷. His research involved a major question astronomers could not answer: What are nebulae?

The astronomical⁹ term "nebulae", Hubble explained, had come down through the centuries. It was the name given to permanent, cloudy areas in the sky outside our solar system. Some astronomers thought nebulae were part of our Milky¹⁰ Way Galaxy¹¹. Others thought they were island universes farther away in space.

In his research paper, Hubble said the issue could be decided only by more powerful instruments. And those instruments had not yet been developed.

VOICE TWO:

In nineteen seventeen, the United States was fighting in World War One in Europe. Edwin Hubble joined the American army and served in France.

Earlier, astronomer George Ellery Hale had offered Hubble a position at the Mount¹² Wilson Observatory in southern California. When Hubble returned to the United States after World War One, he accepted Hale's offer. Hubble was thirty years old. He was just beginning the work that would make him famous.

VOICE ONE:
　
Edwin Hubble

In his first observations from Mount Wilson, Hubble used a telescope with a mirror one hundred fifty-two centimeters across. He studied objects within our own galaxy. And he made an important discovery about nebulae.

Hubble said the light that appeared to come from nebulae really came from stars near the nebulae. The nebulae, he said, were clouds of atoms and dust. They were not hot enough -- like stars-- to give off light.

Soon after, Hubble began working with a larger and more powerful telescope at Mount Wilson. Its mirror was two hundred fifty centimeters across. It was the most powerful telescope in the world for twenty-five years. It had the power Hubble needed to make his major discoveries.

VOICE TWO:

From nineteen twenty-two on, Edwin Hubble began examining more and more distant objects. His first great discovery was made when he recognized a Cepheid variable star. It was in the outer area of the great nebula⁸ called Andromeda. Cepheid variable stars are stars whose brightness¹³ changes at regular periods.

An astronomer at Harvard College, Henrietta Leavitt, had discovered that these periods of brightness could be used to measure the star's distance from Earth. Hubble made the measurements. They showed that the Andromeda nebula lay far outside our Milky Way Galaxy.

Hubble's discovery ended a long dispute. He proved wrong those who believed nebulae lay inside the Milky Way. And he proved that nebulae were galaxies¹⁴ themselves. Astronomers now agree that far distant galaxies do exist.

VOICE ONE:
　
A NASA image of the Andromeda Galaxy

Hubble then began to observe more details about galaxies. He studied their shape and brightness. By nineteen twenty-five, he had made enough observations to say that the universe is organized into galaxies of many shapes and sizes.

As stars differ from one another, he said, so do galaxies. Some are spiral¹⁵ galaxies like the Milky Way and Andromeda. They have a center, and arms of matter that seem to circle the center like a pinwheel. Others are shaped like baseballs or eggs. A few have no special shape.

VOICE TWO:

Hubble proposed a system to describe galaxies by their shape. His system still is used today. He also showed that galaxies are similar in the kinds of bright objects they contain. All galaxies, he said, are related to each other, much as members of a family are related to each other.

In the late nineteen twenties, Hubble studied the movement of galaxies through space. His investigation¹⁶ led to the most important astronomical discovery of the Twentieth century -- the expanding universe.

VOICE ONE:

Earlier observations about the movement of galaxies had been done by V. M. Silpher. He discovered that galaxies are moving away from Earth at speeds between three hundred kilometers a second and one thousand eight hundred kilometers a second.

Hubble understood the importance of Silpher's findings. He developed a plan for measuring both the distance and speed of as many galaxies as possible. With his assistant at Mount Wilson, Milton Humason, Hubble measured the movement of galaxies. The two men did this by studying what Hubble called the "red shift." It also is known as the "Doppler effect."

The Doppler effect explains changes in the length of light waves or sound waves as they move toward you or away from you. Light waves from an object speeding away from you will stretch into longer wavelengths¹⁷. They appear red. Light waves from an object speeding toward you will have shorter wavelengths. They appear blue.

VOICE TWO:

Observations of forty-six galaxies showed Hubble that the galaxies were traveling away from Earth. The observations also showed that the speed was linked directly to the galaxies' distance from Earth. Hubble discovered that the farther away a galaxy is, the greater its speed. This scientific rule is called "Hubble's Law."

Hubble's discovery meant a major change in our idea of the universe. The universe had not been quiet and unchanging since the beginning of time, as many people had thought. It was expanding. And that, Hubble said, meant it probably began with an explosion of unimaginable force. The explosion often is called "the big bang."

VOICE ONE:

Hubble's work did not end with this discovery. He continued to examine galaxies. He continued to gain new knowledge about them. Astronomers from all over the world went to study with him.

Hubble left the Mount Wilson Observatory during World War Two. He did research for the United States War Department. He returned after the war. Then, he spent much of his time planning a new, much larger telescope in southern California. The telescope was completed in nineteen forty-nine. It had a mirror five hundred centimeters across. It was named after astronomer George Ellery Hale.

VOICE TWO:

Edwin Hubble was the first person to use the Hale Telescope. He died in nineteen fifty-three while preparing to spend four nights looking through the telescope at the sky.

Hubble's work led to new research on the birth of the universe. One astronomer said scientists have been filling in the details ever since. And, he said, there is a long way to go.

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ANNOUNCER:

This Special English program was written by Marilyn Rice Christiano. Your narrators were Richard Rael and Tony Riggs. Listen again next week for another EXPLORATIONS program on the Voice of America.

1 astronomer   

n.天文学家

参考例句：

• A new star attracted the notice of the astronomer.新发现的一颗星引起了那位天文学家的注意。
• He is reputed to have been a good astronomer.他以一个优秀的天文学者闻名于世。

2 astronomers   

n.天文学者，天文学家( astronomer的名词复数 )

参考例句：

• Astronomers can accurately foretell the date,time,and length of future eclipses. 天文学家能精确地预告未来日食月食的日期、时刻和时长。 来自《简明英汉词典》
• Astronomers used to ask why only Saturn has rings. 天文学家们过去一直感到奇怪，为什么只有土星有光环。 来自《简明英汉词典》

3 astronomy   

n.天文学

参考例句：

• Mathematics is connected with astronomy.数学与天文学有联系。
• Astronomy is an abstract subject.天文学是一门深奥的学科。

4 boxer   

n.制箱者，拳击手

参考例句：

• The boxer gave his opponent a punch on the nose.这个拳击手朝他对手的鼻子上猛击一拳。
• He moved lightly on his toes like a boxer.他像拳击手一样踮着脚轻盈移动。

5 decided   

adj.决定了的，坚决的；明显的，明确的

参考例句：

• This gave them a decided advantage over their opponents.这使他们比对手具有明显的优势。
• There is a decided difference between British and Chinese way of greeting.英国人和中国人打招呼的方式有很明显的区别。

6 Oxford   

n.牛津（英国城市）

参考例句：

• At present he has become a Professor of Chemistry at Oxford.他现在已是牛津大学的化学教授了。
• This is where the road to Oxford joins the road to London.这是去牛津的路与去伦敦的路的汇合处。

7 observatory   

n.天文台，气象台，瞭望台，观测台

参考例句：

• Guy's house was close to the observatory.盖伊的房子离天文台很近。
• Officials from Greenwich Observatory have the clock checked twice a day.格林威治天文台的职员们每天对大钟检查两次。

8 nebula   

n.星云，喷雾剂

参考例句：

• A powerful telescope can resolve a nebula into stars.一架高性能的望远镜能从星云中分辨出星球来。
• A nebula is really a discrete mass of innumerous stars.一团星云实际上是无数星体不连续的集合体。

9 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。

10 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。

11 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。

12 mount   

n.山峰，乘用马，框，衬纸；vi.增长，骑上（马）；vt.提升，爬上，装备

参考例句：

• Their debts continued to mount up.他们的债务不断增加。
• She is the first woman who steps on the top of Mount Jolmo Lungma.她是第一个登上珠穆朗玛峰的女人。

13 brightness   

n.明亮，亮度，聪颖，光泽度，灯火通明

参考例句：

• The brightness of the paint has worn off a little.油漆的光泽有些磨损了。
• Her eyes squinted against the brightness.亮光刺得她眯起眼睛。

14 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。

15 spiral   

adj.螺旋的；n.螺旋（线）；vi.盘旋上升（或下降）

参考例句：

• The production in this factory is spiral.这个厂的产量呈盘旋上升。
• Their profits began to spiral down disastrously.他们的利润开始螺旋形地急剧下降。

16 investigation   

n.调查，调查研究

参考例句：

• In an investigation,a new fact became known, which told against him.在调查中新发现了一件对他不利的事实。
• He drew the conclusion by building on his own investigation.他根据自己的调查研究作出结论。

17 wavelengths   

n.波长( wavelength的名词复数 )；具有相同的/不同的思路；合拍；不合拍

参考例句：

• I find him difficult to talk to—we're on completely different wavelengths. 我没法和他谈话，因为我们俩完全不对路。 来自《简明英汉词典》
• Sunlight consists of different wavelengths of radiation. 阳光由几种不同波长的射线组成。 来自辞典例句