VOA慢速英语2012 SCIENCE IN THE NEWS - Venus Transits Sun for Last Time This Century

 

SCIENCE IN THE NEWS - Venus Transits² Sun for Last Time This Century

JUNE SIMMS: This is SCIENCE IN THE NEWS, in VOA Special English. I’m June Simms.

SHIRLEY GRIFFITH: And I’m Shirley Griffith. Today, we tell about the planet Venus and what the American space agency is calling a once in a lifetime event. We also tell about other events of interest to sky watchers.

(MUSIC)

JUNE SIMMS: Millions of people around the world are preparing for a rare event high in the sky. Some have purchased telescopes or special equipment to witness the event. Others have organized viewing parties to watch what astronomers⁴ are calling a transit¹ of Venus. This is when the planet Venus passes directly between the Earth and the sun. The transit of Venus will take place on June fifth and sixth. It is the last time this century that people on Earth will be able to observe Venus as it passes across the face of the sun. The next transit will take place more than one hundred years from now.

Jim Green works for the National Aeronautics⁵ and Space Administration. He directs NASA’s Planetary Science Division.

JIM GREEN: “Because Venus’ orbit is inclined to ours, we only see it at very special times when the two orbits connect to one another – we call nodes - and everything lines up perfectly⁶. So this actually is the last transit that we will see in our lifetime. The next one will be in twenty one seventeen.”

SHIRLEY GRIFFITH: A transit of Venus is similar to a solar eclipse of the moon, which blocks light from the sun. Venus is almost four times the size of the moon. However, it blocks less light than the moon does. As Jim Green notes, Venus’s distance from us makes the planet appear much smaller. 

JIM GREEN: Most of the time the size of the moon, as we see it in its orbit, is about the same angular size as the sun. And, so when it blocks it out we only see the atmosphere of the sun. But, for Venus it’s so much further away and therefore it appears to be smaller.” 

From Earth, Venus will appear as a small black dot as it slowly moves from one edge of the sun to the other. It will take more than six hours for the planet to complete the trip.

(MUSIC)

JUNE SIMMS: Venus is the second planet from the sun and the closest planet to Earth. It also is the only planet in the solar system named for a female. The name comes from the ancient Roman goddess of love and beauty. The planet is said to have been named for her because it shone brighter than all the planets known to ancient astronomers.

In fact, people once believed Venus to be two different stars, with one appearing at sunset and the other at sunrise. That is because the planet shines with differing intensities⁷ of brightness at different times of the day.

SHIRLEY GRIFFITH: Venus has similar qualities to our planet and is often called Earth’s sister. It has volcanoes, mountains, craters⁸ and sands just like Earth. The two planets are also similar in size, mass, chemistry and gravity. 

Venus and the planet Mercury are called inferior planets because they are closer to the sun than the Earth. Venus is the hottest planet in our solar system, even hotter than Mercury.

NASA’s Jim Green says it is even hot enough to melt lead. Although Mercury is closer to the sun, the thick atmosphere on Venus traps more of the sun’s heat.

JIM GREEN: “Sunlight penetrates⁹ through the atmosphere, heats the ground on Venus and then that heat is not allowed to escape because the carbon dioxide keeps it in. It’s exactly the same principle as getting into your car on a hot summer day. It’s very hot inside because the heat is not allowed to go through the windows of your car but the light does.”

JUNE SIMMS: The surface temperature of Venus can reach four hundred seventy degrees Celsius¹⁰. NASA first documented the planet’s extreme temperatures in nineteen sixty-two. The Mariner¹¹ 2 spacecraft became the first successful mission to another planet when it flew close to Venus in December of that year. Jim Green says space exploration has not been the same since then. 

JIM GREEN: Before nineteen sixty-two, everything that we knew about planets we got from telescopes. But from nineteen sixty-two on we’ve been able to fly by, orbit, land, rove and return samples all over the place, on various planets and comets and asteroids¹². So this has really radically¹³ changed our view of the solar system.”

In nineteen seventy, the Soviet¹⁴ Union became the first country to land a spacecraft on Venus. Its Venera 7 spacecraft sent back twenty-three minutes of information from the surface before being destroyed by the planet’s heat.

SHIRLEY GRIFFITH: Most of what we know about the qualities of Venus was discovered during and after those two historic events. However, knowledge of the Venus transit dates back centuries.

English astronomer³ Jeremiah Horrocks is one of two people credited with being the first to witness a Venus transit in sixteen thirty nine. He wrote of seeing a “spot of unusual magnitude and of a perfectly circular shape, which had already fully¹⁵ entered upon the sun’s disc on the left.”

Newer evidence suggests that ancient Babylonians may have witnessed a Venus transit about three thousand five hundred years ago. But that evidence cannot be confirmed.

JUNE SIMMS: NASA’s Jim Green says early astronomers used Venus transit observations to help estimate the distance from the Earth to the sun, and other objects in space.

JIM GREEN: “In the early sixteen hundreds when it was first observed it was believed that the distance between the Earth and the sun was five million miles. Well, we know today that it’s about ninety-three million miles. So, over time we have been able to get it right.”

He also says that being able to establish the distance between the Earth and the sun was a major development in planetary research.

JIM GREEN: “That turns out to be incredibly important. That’s our yardstick¹⁶. We call that one astronomical¹⁷ unit and we measure things by that. We measure the distance to our other planets. Jupiter is five astronomical units away. Pluto¹⁸ is forty astronomical units away.”

SHIRLEY GRIFFITH: Venus transits are extremely rare. They happen in pairs, or groups of two, every one hundred five years to one hundred twenty two years. The transits that make up the pair happen eight years apart. Jim Green says over time the celestial¹⁹ event repeats itself.

JIM GREEN: “It starts out every hundred and twenty-two years. And then it goes every eight years. And then it’s every hundred and five years. And then it goes back to eight years. So there is indeed a pattern and it’s base on the two orbits - Earth and Venus, and their orientation²⁰ and their eccentricity²¹.”

The first transit in this most recent grouping took place in two thousand four. The last transit before that was in eighteen eighty-two.

Mercury also transits the sun. However, those events are much more common. They take place about thirteen times each century.

JUNE SIMMS: NASA says there have been only seven Venus transits since the invention of the telescope in sixteen ten. It is such a rare event that very few people alive today will get another chance to see it after June sixth.

This time, the Venus transit begins on June fifth at twenty two hundred nine, Universal Time. It lasts almost seven hours, and can be seen from every continent.

People in North and South America will be able to see Venus as it begins moving across the sun. However, the sun will go down before Venus completes its pass. People in Europe and parts of Asia, Africa and Australia will see the end of the Venus transit as the sun rises in their areas.

SHIRLEY GRIFFITH: Experts warn people to follow safety rules if they plan to watch the event. They say looking directly at the sun could damage your eyes, even cause blindness. And, they say, traditional sunglasses do not provide the necessary protection.

They advise transit observers to wear special eye glasses made with lenses that help filter the sun’s light. Some telescopes, binoculars²² and cameras also have sun filters.

Jim Green says a number of sun spots will also be visible. He says observers should be careful not to confuse the two. For computer users, there is a software app available online that will tell you the best time to watch for the Venus transit in your area. And, NASA officials have made plans for a webcast of the event from a mountainside observatory²³ in Hilo, Hawaii. The agency says this location will provide a wonderful view of this century’s last Venus transit from beginning to end.

(MUSIC)

JUNE SIMMS: Two thousand twelve has been an exciting year for celestial events. We began the year with the Quandrantid Meteor Shower in January. At the time, sixty to two hundred meteors fell toward Earth every hour.

In February, a large number of unusual fireballs were reported in skies over the United States. This yearly event is known as the “Fireballs of February.”

NASA officials say the fireballs resulted from big space rocks hitting the Earth’s atmosphere. Officials say what was unusual about these fireballs was how slowly they moved and how deeply they penetrated²⁴ Earth’s atmosphere. They were also longer lasting²⁵ and brighter than other fireballs.

SHIRLEY GRIFFITH: March brought what astronomers have called the brightest Venus-Jupiter Conjunction for many years to come. A conjunction happens when two planets appear to line up close to each other in the sky. In reality, they are still millions of kilometers apart.

In April, there was another meteor shower -- this one known as Lyrids. And in May, sky watchers around the world witnessed an eclipse of the moon. The moon was as far from the Earth as it ever gets. This created the largest possible bright ring around the edges of the moon as it passed in front of the sun.

(MUSIC)

SHIRLEY GRIFFITH: I’m Shirley Griffith with June Simms, who wrote and produced this SCIENCE IN THE NEWS program. To see pictures of what astronomers have called “the Ring of Fire,” and images from the Venus transit of two thousand four, visit www.voanews.cn. Join us again next week for more news about science in Special English on the Voice of America.

1 transit   

n.经过，运输；vt.穿越，旋转；vi.越过

参考例句：

• His luggage was lost in transit.他的行李在运送中丢失。
• The canal can transit a total of 50 ships daily.这条运河每天能通过50条船。

2 transits   

通过（transit的复数形式）

参考例句：

• The anomalistic year is the time between successive transits of the Earth through the perihelion. 近点年是地球连续两次通过近日点之间的时间。
• Paradigm study gradually transits to exemplification study in civil society theory. 当前我国的市民社会理论正逐步从范式研究转向范例研究。

3 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。

4 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》

5 aeronautics   

n.航空术，航空学

参考例句：

• National Aeronautics and Space undertakings have made great progress.国家的航空航天事业有了很大的发展。
• He devoted every spare moment to aeronautics.他把他所有多余的时间用在航空学上。

6 perfectly   

adv.完美地，无可非议地，彻底地

参考例句：

• The witnesses were each perfectly certain of what they said.证人们个个对自己所说的话十分肯定。
• Everything that we're doing is all perfectly above board.我们做的每件事情都是光明正大的。

7 intensities   

n.强烈( intensity的名词复数 )；（感情的）强烈程度；强度；烈度

参考例句：

• At very high intensities, nuclear radiations cause itching and tingling of the skin. 当核辐射强度很高时，它能使皮肤感到发痒和刺痛。 来自辞典例句
• They ask again and again in a variety of ways and intensities. 他们会以不同的方式和强度来不停地问，直到他得到自己想要的答案为止。 来自互联网

8 craters   

n.火山口( crater的名词复数 )；弹坑等

参考例句：

• Small meteorites have left impact craters all over the planet's surface. 这个行星的表面布满了小块陨石留下的撞击坑。 来自《简明英汉词典》
• The battlefield was full of craters made by exploding shells. 战场上布满弹坑。 来自《现代英汉综合大词典》

9 penetrates   

v.穿过( penetrate的第三人称单数 )；刺入；了解；渗透

参考例句：

• This is a telescope that penetrates to the remote parts of the universe. 这是一架能看到宇宙中遥远地方的望远镜。 来自《简明英汉词典》
• The dust is so fine that it easily penetrates all the buildings. 尘土极细，能极轻易地钻入一切建筑物。 来自辞典例句

10 Celsius   

adj.摄氏温度计的，摄氏的

参考例句：

• The temperature tonight will fall to seven degrees Celsius.今晚气温将下降到七摄氏度。
• The maximum temperature in July may be 36 degrees Celsius.七月份最高温度可能达到36摄氏度。

11 mariner   

n.水手号不载人航天探测器，海员，航海者

参考例句：

• A smooth sea never made a skillful mariner.平静的大海决不能造就熟练的水手。
• A mariner must have his eye upon rocks and sands as well as upon the North Star.海员不仅要盯着北极星，还要注意暗礁和险滩。

12 asteroids   

n.小行星( asteroid的名词复数 )；海盘车，海星

参考例句：

• Asteroids,also known as "minor planets",are numerous in the outer space. 小行星，亦称为“小型行星”，在外太空中不计其数。
• Most stars probably have their quota of planets, meteorids, comets, and asteroids. 多数恒星也许还拥有若干行星、流星、彗星和小行星。

13 radically   

ad.根本地，本质地

参考例句：

• I think we may have to rethink our policies fairly radically. 我认为我们可能要对我们的政策进行根本的反思。
• The health service must be radically reformed. 公共医疗卫生服务必须进行彻底改革。

14 Soviet   

adj.苏联的，苏维埃的；n.苏维埃

参考例句：

• Zhukov was a marshal of the former Soviet Union.朱可夫是前苏联的一位元帅。
• Germany began to attack the Soviet Union in 1941.德国在1941年开始进攻苏联。

15 fully   

adv.完全地，全部地，彻底地；充分地

参考例句：

• The doctor asked me to breathe in,then to breathe out fully.医生让我先吸气，然后全部呼出。
• They soon became fully integrated into the local community.他们很快就完全融入了当地人的圈子。

16 yardstick   

n.计算标准，尺度；评价标准

参考例句：

• This is a yardstick for measuring whether a person is really progressive.这是衡量一个人是否真正进步的标准。
• She was a yardstick against which I could measure my achievements.她是一个我可以用来衡量我的成就的准绳。

17 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。

18 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。

19 celestial   

adj.天体的；天上的

参考例句：

• The rosy light yet beamed like a celestial dawn.玫瑰色的红光依然象天上的朝霞一样绚丽。
• Gravity governs the motions of celestial bodies.万有引力控制着天体的运动。

20 orientation   

n.方向，目标；熟悉，适应，情况介绍

参考例句：

• Children need some orientation when they go to school.小孩子上学时需要适应。
• The traveller found his orientation with the aid of a good map.旅行者借助一幅好地图得知自己的方向。

21 eccentricity   

n.古怪，反常，怪癖

参考例句：

• I can't understand the eccentricity of Henry's behavior.我不理解亨利的古怪举止。
• His eccentricity had become legendary long before he died.在他去世之前他的古怪脾气就早已闻名遐尔了。

22 binoculars   

n.双筒望远镜

参考例句：

• He watched the play through his binoculars.他用双筒望远镜看戏。
• If I had binoculars,I could see that comet clearly.如果我有望远镜，我就可以清楚地看见那颗彗星。

23 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。

24 penetrated   

adj. 击穿的，鞭辟入里的 动词penetrate的过去式和过去分词形式

参考例句：

• The knife had penetrated his chest. 刀子刺入了他的胸膛。
• They penetrated into territory where no man had ever gone before. 他们已进入先前没人去过的地区。

25 lasting   

adj.永久的，永恒的；vbl.持续，维持

参考例句：

• The lasting war debased the value of the dollar.持久的战争使美元贬值。
• We hope for a lasting settlement of all these troubles.我们希望这些纠纷能获得永久的解决。