研究人员发现适合生物存活的类地行星
文章来源:未知 文章作者:meng 发布时间:2010-09-30 06:19 字体: [ ]  进入论坛
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太空探索研究人员最近发现了一颗大小类似地球的行星,这颗行星围绕离地球20光年的一颗恒星运转,其表面温度适宜产生液态水源,因而很有可能是另一个适合生物存活的星球。

An artist's impression of Gliese 581g, which <a href=astronomers2 say is near Earth - relatively3 speaking - at 120 trillion miles." src="http://www.enread.com/upimg/allimg/100930/4_100930062002_1.jpg" width="460" height="276" />
An artist's impression of Gliese 581g, which astronomers say is near Earth - relatively speaking - at 120 trillion miles.

Astronomers have discovered a potentially habitable planet of similar size to Earth in orbit around a nearby star.

A team of planet hunters spotted4 the alien world circling a red dwarf5 star(矮星) called Gliese 581, 20 light years away.

The planet is in the "Goldilocks zone" of space around a star where surface temperatures are neither too hot nor too cold for liquid water to form.

"Our findings offer a very compelling(引人注目的) case for a potentially habitable planet," said Steven Vogt, an astronomer1 at the University of California, Santa Cruz. "The fact that we were able to detect this planet so quickly and so nearby tells us that planets like this must be really common."

If confirmed, the planet would be the most Earth-like that has ever been discovered in another solar system and the first strong contender for a habitable one.

More than 400 exoplanets(外部行星) have been discovered by astronomers, but most are gas giants, like Jupiter, that would be inhospitable(荒凉的,冷淡的) to life as we know it.

Astronomers used the Keck telescope in Hawaii to study the movement of Gliese 581 in exquisite6(精致的,细腻的) detail and from their observations inferred the presence of a number of orbiting planets. The team report two new planets in the Astrophysical Journal, bringing the total number known to be circling the star to six.

One of the planets, named Gliese 581g, has a mass of three to four times that of Earth and takes 37 days to orbit the star. Astronomers believe it is a rocky planet with enough gravity to retain an atmosphere.

Unlike the previously7 discovered planets, Gliese 581g lies squarely in the region of space where life can thrive. "We had planets on both sides of the habitable zone — one too hot and one too cold — and now we have one in the middle that's just right," Vogt said.

One side of the planet is always facing the star, much as one side of the moon constantly faces Earth. This means that the far side of the planet is constantly in darkness. The most habitable region of the planet would be the line between the light and dark regions.

"Any emerging life forms would have a wide range of stable climates to choose from and to evolve around, depending on their longitude8(经度) ," Vogt said.

The average temperature on the planet is estimated to be between -31 to -12C, but the ground temperature would vary from blazing hot on the bright side and freezing on the dark side.

"The number of systems with potentially habitable planets is probably on the order of 10 or 20 percent, and when you multiply that by the hundreds of billions of stars in the Milky9 Way(银河系) , that's a large number. There could be tens of billions of these systems in our galaxy," said Vogt.



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1 astronomer DOEyh     
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 569155f16962e086bd7de77deceefcbd     
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 relatively bkqzS3     
adv.比较...地,相对地
参考例句:
  • The rabbit is a relatively recent introduction in Australia.兔子是相对较新引入澳大利亚的物种。
  • The operation was relatively painless.手术相对来说不痛。
4 spotted 7FEyj     
adj.有斑点的,斑纹的,弄污了的
参考例句:
  • The milkman selected the spotted cows,from among a herd of two hundred.牛奶商从一群200头牛中选出有斑点的牛。
  • Sam's shop stocks short spotted socks.山姆的商店屯积了有斑点的短袜。
5 dwarf EkjzH     
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。
6 exquisite zhez1     
adj.精美的;敏锐的;剧烈的,感觉强烈的
参考例句:
  • I was admiring the exquisite workmanship in the mosaic.我当时正在欣赏镶嵌画的精致做工。
  • I still remember the exquisite pleasure I experienced in Bali.我依然记得在巴厘岛所经历的那种剧烈的快感。
7 previously bkzzzC     
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。
8 longitude o0ZxR     
n.经线,经度
参考例句:
  • The city is at longitude 21°east.这个城市位于东经21度。
  • He noted the latitude and longitude,then made a mark on the admiralty chart.他记下纬度和经度,然后在航海图上做了个标记。
9 milky JD0xg     
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。
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