英语听力文摘 English Digest 311、宇宙生命奥秘

　　The Habitable Zone
宇宙生命奥秘
适居带(HZ)是天文学上给一种空间的名称，指的是那里的情况有利于生物的存在，或许可以发现像地球这样的生命体。有两种区域是有可能的，一个是在行星系内，另一个则存在于星系之中。在适合的区域内的行星和天然卫星是最佳的候选者，这些地球外的生命有能力生活在类似我们的环境下。天文学家相信生命最可能发生在像太阳系这样的星周盘适居带(CHZ)和大星系的星系适居带 (GHZ)内。适居带也许是指"生命带"、"绿带"或"Goldilocks带"(因为既不太热也不太冷，就是刚好)。在我们的太阳系，适居带被认为从0.95天文单位延伸至1.37天文单位。
Y: Do you think there's life on other planets Don?
D: It seems perfectly¹ reasonable that there would be Ya?l. what with how unfathomably large the universe is.Don't you think？
Y:I do.But then again, life is a tricky² thing. So much has to fall into place for the conditions for life as we know it to be possible.For instance, a planet has to be just the right distance from the star it revolves³ around.
D:How is that?
Y:If it’s too close to its star, the heat from the star would cause any water on the planet to boil away. If it’s too far away, the opposite problem occurs: the cold temperature would cause water to freeze. The range of distance from a star that will allow water to remain a liquid is called the habitable zone.
D:So we Earthlings are lucky I guess that we are just the right distance away from the sun.

　　Y:Very lucky it seems.In 2007, scientists discovered the first two Earth-like planets outside our solar system that appear to be located near or within their star’s habitable zone. Previously⁴ discovered planets have had masses more akin⁵ to Jupiter’s. The planets orbit the same star and are known as Gliese 581c and Gliese 581d.
D:Wow,so there is other life out there?
Y:Not so fast, upon further investigation⁶, it seems that Gliese 581d may be the only one of the two actually in the habitable zone, and its orbit seems to take it in and out of the zone.  Not to mention as I said, a lot of factors must come into play for life to exist. Being within the habitable zone is just one of them.
译文
Y:Don，你认为其他行星上会有生命存在吗？
D:似乎完全有理由相信有生命存在。宇宙如此之大，深不可测，不是吗？
Y:的确如此。但是话又说回来，生命的存在是一件极其有难度的事。据我们所知，生命存在的可能性需要满足众多适合生存的条件。比如说，行星与其所围绕旋转的恒星之间的距离是否适当。
D:这有什么关系？
Y:如果太近，来自恒星的热量会导致行星上水分蒸发，与之相反，要是距离太远，温度太低会致使水冻结。与恒星之间的距离要能保持水呈现的是液体状态，这个范围被称作适居带。
D:那我们地球岂不是很幸运，与太阳之间的距离正当适宜。
Y:是非常的幸运。2007年，科学家们在太阳系以外首次发现两颗类似地球，可能位于适居带附近的行星，而之前发现的行星更类似于木星。这两颗行星都围绕格利泽581恒星转动，因此他们被称作格利泽581d和格利泽581c。
D:哇！那探索到有生命存在吗？
Y:没那么快。据进一步调查研究发现，格利泽581d可能是二者中在适居区以内的行星，而且其运行轨道使其在适居区内游离。更何况正如我所说的，生命存在还有诸多因素要考虑，在适居区只是其中之一。

1 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。

2 tricky   

adj.狡猾的，奸诈的；(工作等)棘手的，微妙的

参考例句：

• I'm in a rather tricky position.Can you help me out?我的处境很棘手，你能帮我吗？
• He avoided this tricky question and talked in generalities.他回避了这个非常微妙的问题，只做了个笼统的表述。

3 revolves   

v.（使）旋转( revolve的第三人称单数 )；细想

参考例句：

• The earth revolves both round the sun and on its own axis. 地球既公转又自转。 来自《现代汉英综合大词典》
• Thus a wheel revolves on its axle. 于是，轮子在轴上旋转。 来自《简明英汉词典》

4 previously   

adv.以前，先前（地）

参考例句：

• The bicycle tyre blew out at a previously damaged point.自行车胎在以前损坏过的地方又爆开了。
• Let me digress for a moment and explain what had happened previously.让我岔开一会儿，解释原先发生了什么。

5 akin   

adj.同族的，类似的

参考例句：

• She painted flowers and birds pictures akin to those of earlier feminine painters.她画一些同早期女画家类似的花鸟画。
• Listening to his life story is akin to reading a good adventure novel.听他的人生故事犹如阅读一本精彩的冒险小说。

6 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。