遥远的行星上发现甲烷(图)   

系外行星HD 189733b 大气中拥有有机分子——甲烷。但是那里条件太恶劣，不会形成生命。该行星是一颗“热木星”，距地球63光年。

Methane spotted on distant planet

An organic molecule has been spotted for the first time in the atmosphere of a planet outside our solar system, a key step toward possibly finding signs of life on a distant world, scientists say.	科学家们称，在太阳系以外一颗行星的大气中首次发现了一种有机分子；在遥远的星球上可能会找到生命的迹象，但发现有机分子是关键的一步。
Astronomers using the Hubble Space Telescope found methane in the atmosphere of a planet called HD 189733b.    This planet is about the size of Jupiter and is 63 light-years from Earth, the researchers write today in the journal Nature.	天文学家们利用哈勃太空望远镜在一颗被称为HD 189733b的行星大气中发现了甲烷。研究人员在今天出版的《自然》杂志中写道：该行星的大小约相当于木星，距地球63光年。
But the scientists are quick to point out that this distant planet, with atmospheric temperatures around 1000°C, is not thought to be a candidate for hosting any form of life.	然而，研究人员很快指出：这颗遥远的行星大气温度在1000摄氏度左右，被认为不是生命的候选场所，不会拥有任何形式的生命。
"For this specific planet we observed, methane cannot be produced biologically," says Dr Giovanna Tinetti of University College London. "The idea is to repeat the same kind of observations in the future for planets which are less hostile to the development and evolution of life."	“对于我们所观察的这颗特殊行星来说，甲烷不会产生生命，”伦敦大学学院的乔凡娜·提奈提博士说，“我们的想法是，将来可以重复利用同样的观察方法，以寻找对生命发育和进化较为有利的行星。”
HD 189733b is one of more than 270 planets to be discovered orbiting stars other than our sun, called extrasolar planets. It is a 'hot Jupiter' type, similar to the gas giant Jupiter in our solar system but reaching scorching temperatures because they orbit so closely to their stars. This one whizzes around its star roughly every two Earth days.	HD 189733b是业已发现的270多颗围绕着太阳系以外恒星旋转的行星之一，被称为系外行星。该行星属于一类“热木星”，跟太阳系中的气态巨星——木星类似，但达到了极高的温度，因为它们在很近的距离上围绕其恒星旋转。HD 189733b大约每隔两个地球日便绕其恒星一周。
Methane, composed of carbon and hydrogen, has been detected on many of the planets in our solar system.	甲烷由碳和氢组成，曾发现于我们太阳系中的多颗行星上。
"Under the right conditions, methane can contribute to the formation of amino acids," an important building block of life, says another member of the research group, Dr Mark Swain of NASA's Jet Propulsion Laboratory in Pasadena, California.	研究小组的另一个成员、加州帕萨迪纳美国国家航空航天管理局喷气动力实验室的马克·斯温博士说：“在合适的条件下，甲烷可以促进氨基酸的形成。”氨基酸是重要的生命基础材料。
The scientists also confirmed the previously reported discovery of water molecules in the planet's atmosphere.	以前的报道中说，在HD 189733b大气中发现了水分子。科学家们也证实了该发现。
They made their observations as the planet passed in front of its parent star in what is called a transit. The scientists used a method called transit spectroscopy, breaking light up into its various colours.	HD 189733b从其主恒星前面经过时，即发生所谓的凌日现象时，科学家们进行了观察。他们利用了一种方法，叫做凌日光谱分析法，将光线分解成各种各样的颜色。
"You can think of the prism making a rainbow spectrum when you shine light through it. And we do this when the planet passes in front of its parent star. So what we see is the starlight filtered through the planet's atmosphere," Swain says. "The molecules in the atmosphere of the planet leave a fingerprint in the spectrum."	“你可以想象一下，当光线射穿棱镜的时候，棱镜会发出五彩缤纷的光谱。该行星在其主恒星前面通过时，我们观察到了五彩光谱，所观察到的是恒星光线穿过行星大气时的情形，”斯温说，“行星大气中的分子都会在光谱上留下一种印记。”