評論
打印
Narrator:Listen to part of a lecture in an astronomy class.
獨白:請聽下面一段天文學課堂上的講解。
Professor:Many people have been fascinated about Venus for centuries because of its thick cloud cover, this so-called planet of mystery and all of that.
教授:幾個世紀來許多人都對厚云層覆蓋的金星有著深厚的興趣，它被稱之為神秘的星球。
Well, what's under those clouds? What's the surface of the planet like?
那么，云層下面是什么呢？金星的表面是什么樣子呢？
Some questions about the surface are still unresolved but, but we have learned a lot about it in the past several years.
關于金星地表的一些問題還沒有被解決，但是在過去的幾年中我們也對之有所了解。
First of all, let me talk about how we have been able to get past those clouds.
首先，讓我說一下我們已經能夠穿過這些厚厚的云層。
First, there were Soviet modules2 that landed directly on the surface and sent back some images of what was around them.
首先，是蘇聯的“金星二號”探測器，他直接著陸在金星表面并發回了它周圍的圖像。
Second, we did some radar imaging from satellites from above.
其次，我們用金星上空的衛星金星了雷達成像。
Radar can get through the clouds. So what have we learned? Yes, Karen?
雷達可以穿過云層。所以我們都知道了什么呢？好，凱倫？
Student:Well, I remember reading that there's not really a lot going on, that the surface of Venus is just flat and smooth in a lot of places.
學生:嗯，我記得讀到過，并沒有多大的收獲，金星的地表的大部分地區十分平坦。
Professor:Yeah, smooth in a lot of places.
教授:是的，大部分地區十分平坦。
But that's not, um... that's not the whole picture.
但是，并不全是這樣。
In other areas, you've got canyons, ripped valleys, meteo craters, uh, lava domes.
在其他地區，有火山、輪廓清晰的山谷、隕石坑、熔巖穹丘。
these lava formations that look like giant pancakes.
這些熔巖的形狀就像是巨大的薄餅。
And also volcanoes.
火山也是如此。
Well, one of the most interesting features on the surface are in fact the shield volcanoes.
金星地表最有意思的特征是火山的地盾。
Shield volcanoes formed when magma comes out of the ground in the same spot over and over again.
地盾是由于巖漿反復從一個地方噴出地表而形成的。
Remember, magma is hot molten rock that's underground, and it is called lava when it reaches the surface.
記住，巖漿是地下熱的熔化了的巖石，當流出地表后就稱為巖漿。
Uh, so the lava builds up, and hardens, and a volcano forms.
這樣，巖漿構成并冷卻成火山。
Now, the lava on Venus is thin.
金星的巖漿比較稀薄。
It spreads out easily.
它很容易就會噴出。
So shield volcanoes have very gentle sloping sides.
所以火山的地盾比較平緩。
They are called shield volcanoes, because viewed from above, they kind of resemble shields, you know, like a warrior's shield.
他們被叫做盾狀火山，是因為從上空看起來他們的形狀比較像盾，就是戰士的盾牌。
But what's particularly interesting about these volcanoes is that most of the volcanoes here on Earth are not shield volcanoes.
十分有趣的是地球上的火山大部分都不是盾狀火山。
Instead, they are other volcano types, like strata volcanoes, for example, which are a result of tectonic plate movement.
相反的，是其他種類的火山，例如，地層火山，是地球板塊運動造成的。
Remember tectonic plates?
還記得地層火山吧？
Underneath the Earth's crust, there are a number of shifting slabs or plates that are slowly moving.
在地殼下方，有許多緩緩移動的板塊。
And in the zones on the edges of the plates where different plates meet and interact, that's where we get most of Earth's volcanoes On Venus.
而在不同板塊連接或互相作用的地區，存在著地球上大部分的火山。
However, volcanoes are not clustered in discrete zones like they are on Earth.
而在金星上，火山并不像在地球上一樣在個別地區集中。
Instead, they are more or less randomly scattered over Venus's surface.
相反地它們很隨機的分布在金星的表面。
Well, that's significant.
很是壯觀。
Venus has mostly shield volcanoes, and they are randomly scattered, that indicates that Venus does not have moving tectonic plates, and that's a big difference compared to Earth.
金星上大部分是盾狀火山，它們的分布十分分散，這說明金星沒有移動的地質板塊，這與地球十分的不同。
Here on Earth, moving tectonic plates are a major geological element, just crucial for the whole surface dynamic, right?
在地球上，活動的地質板塊是只要的地質因素，對整個地表的動態變化十分的重要，對不對？
So why doesn't Venus have them? Well, there are a few theories.
為什么金星沒有地質板塊呢？對此有幾個理論。
One of them is that this has to do with the fact that Venus has no surface water that's needed to kind of lubricate the movement of the plates, you know, like oceans on Earth.
其中一個是說由于火星沒有地表水，地表水可以為地質板塊的運動起到潤滑作用，就像在地球上一樣。
Yeah, I forgot to spell that out. Uh, Venus has no surface water.
哦，我忘了提到，金星上沒有地表水。
Student:Wait a second. Did you say we have shield volcanoes on Earth? Can you give an example?
學生:請等一下。您說地球上有盾狀火山？您能舉一個例子嗎？
Professor:Sure. The volcanoes in the Hawaii islands, in the Pacific Ocean are shield volcanoes.
教授:當然可以了。在太平洋的夏威夷島上的火山就是盾狀火山。
They are formed over a hot spot of magma.
它們是由地下噴出的巖漿構成的。
So while on Earth we have several types of volcanoes, on Venus there's mostly the one type. Uh, Eric?
所以在地球上的火山有很多種，而金星上的火山卻差不多只有一種。艾瑞克？
Student:Are the volcanoes on Venus still active?
學生:金星上的火山是活火山嗎？
Professor:Well, that's an interesting question.
教授:嗯，這個問題很有意思。
There is still some discussion on that point.
對于這個問題還存在著爭論。
But here's what we do now.
這樣講吧。
First, the level of sulfur dioxide gas above Venus's clouds shows large and very frequent fluctuations.
首先，金星云層中的二氧化硫的含量顯示出很大幅度并經常的波動。
It is quite possible that these fluctuations, the huge increase and decrease of sulfur dioxide, happening again and again.
這些波動有可能是由二氧化硫不斷地驟增和驟減引起的。
It's quite possible that this is due to volcanic eruptions, because volcanic eruptions often emit gases.
很有可能這是由火山爆發引起的，因為火山爆發常常會發射出氣體。
If that's the case, volcanism could very well be the root cause of Venus's thick cloud cover.
如果是這樣的話，火山活動很有可能是造成金星厚云蓋的根本原因。
And also we have observed bursts of radio energy from the planet's surface.
而且我們觀察到金星表面會爆發出電磁能量。
These bursts are similar to what we see when volcanoes erupt on Earth.
這種爆發與我們在地球上看到的火山爆發相似。
So this too suggests ongoing volcanic activity.
這也同樣使人聯想到火山活動。
But although this is intriguing evidence, no one's actually observed a Venus volcano erupting yet, so we can't be positive.
但盡管這個證據十分有吸引力，但是到目前為止并沒有人真正的見過金星的火山爆發，所以我們無法肯定。
