VOA慢速英语20060826a

IN THE NEWS - Pluto¹ and Dark Matter Both Star in a Busy Week for AstronomersBy Brianna Blake

Broadcast: Saturday, August 26, 2006

This is IN THE NEWS in VOA Special English.


Pluto compared to other solar system bodies including Earth.

This week, there were two big developments in astronomical³ science. One was a decision to name Pluto a dwarf⁴ planet.

The other was the announcement earlier in the week that scientists have found direct evidence for dark matter. But they say they are still not sure what this mysterious matter is or where it comes from.

Scientists have theorized about dark matter for about seventy years. The idea is that the matter we see does not have enough gravitational pull to keep galaxies⁵ together. Visible matter has been estimated to represent only about five percent of the universe.

The new findings come from NASA's Chandra X-ray Observatory⁶ and other
The Chandra x-ray telescope has sought evidence of dark matter in galaxies like Abell 2029 (Pictur-NASA)

telescopes.

A team of scientists observed a group of galaxies that formed when two galaxy⁷ clusters smashed into each other. They call it the bullet cluster. It contains a bullet-shaped cloud of hot gas from a smaller cluster that passed through the hot gas from a larger one.

The bullet cluster is more than three thousand million light-years away. It formed in the last one hundred million years.

Scientists can observe what they believe to be dark matter only through its gravity. But the team says the crash was violent enough to break dark matter away from normal matter. Normal matter in galaxy clusters is mostly in the form of hot gas and stars.

They call it the strongest evidence yet that most of the matter in the universe is dark.

They say the observations cannot be explained by theories of gravity that remove the need for dark matter. These theories propose that gravity is stronger with huge galaxy clusters than the theories of Isaac Newton or Albert Einstein would suggest.

The findings will appear in the Astrophysical Journal Letters.

Now on to Pluto. This week the International Astronomical Union met in Prague, in the Czech Republic, with the goal to officially define a planet.

Scientists voted to set three requirements for a planet: It must orbit the sun. It must have enough mass so that its own gravity has formed it into a nearly round shape. And it must have cleared the area of other objects around its orbit. That is where Pluto fails: its orbit around the sun crosses paths with Neptune⁸'s.

American Clyde Tombaugh discovered Pluto in nineteen thirty. People have long debated about considering it the ninth planet in our solar system. Now Pluto will be called a dwarf planet along with at least two others: Xena and Ceres.

The changes divide astronomers². But supporters say recent discoveries of large objects in the outer solar system require them.

So the new model of our solar system has eight classical planets. The smaller, rocky worlds are Mercury, Venus, Earth and Mars. The four huge gas planets are Jupiter, Saturn⁹, Uranus¹⁰ and Neptune.

And that's IN THE NEWS in VOA Special English, written by Brianna Blake and online at www.unsv.com. This is Shep O'Neal.

1 Pluto   

n.冥王星

参考例句：

• Pluto is the furthest planet from the sun.冥王星是离太阳最远的行星。
• Pluto has an elliptic orbit.冥王星的轨道是椭圆形的。

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 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。

4 dwarf   

n.矮子，侏儒，矮小的动植物；vt.使…矮小

参考例句：

• The dwarf's long arms were not proportional to his height.那侏儒的长臂与他的身高不成比例。
• The dwarf shrugged his shoulders and shook his head. 矮子耸耸肩膀，摇摇头。

5 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。

6 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。

7 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。

8 Neptune   

n.海王星

参考例句：

• Neptune is the furthest planet from the sun.海王星是离太阳最远的行星。
• Neptune turned out to be a dynamic,stormy world.海王星原来是个有生气、多风暴的世界。

9 Saturn   

n.农神，土星

参考例句：

• 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。
• These comparisons suggested that Saturn is made of lighter materials.这些比较告诉我们，土星由较轻的物质构成。

10 Uranus   

n.天王星

参考例句：

• Uranus is unusual because it is tilted.天王星非常特殊，因为它是倾斜的。
• Uranus represents sudden change and rebellion.天王星代表突然性的改变和反叛。