Scientists from NASA have found evidence of life on Saturn's biggest moon, Titan。

　　Data from NASA's Cassini probe analyzed the complex chemistry on the surface of Titan - the only moon known to have a dense atmosphere. Its surface is covered with mountains, lakes and rivers which has led astronomers to call it 'the most Earth-like world in the solar system'。

　　Liquid on Titan is not water but methane, which leads scientists on a guess that life on the moon could be methane-based. The hydrogen gas flowing down through Titan's atmosphere disappears in the surface, suggesting it could be being breathed by alien bugs。

　　NASA astrobiologist Chris McKay said: 'If these signs do turn out to be a sign of life, it would be doubly exciting because it would represent a second form of life independent from water.'

　　Scientists believe that when the Sun swells up in four billion years, swallowing the Earth, conditions could be ideal on a warmer Titan。

　　Professor John Zarnecki, of the Open University, said: 'We believe the chemistry is there for life to form. It just needs heat and warmth to kick-start the process. In four billion years' time, when the Sun swells into a red giant, Titan could become a paradise.'

　　美国宇航局(NASA)的科学家日前宣称，最新证据表明，土星的最大卫星泰坦(即“土卫六”)存在生命迹象。

　　英国《每日电讯报》5日报道，科学家利用NASA土星探测船“卡西尼号”传回的数据，分析了土星泰坦表层的复杂化学物质。据了解，泰坦是目前所知的唯一拥有高密度大气层的土星卫星。数据显示，该卫星表层有群山、湖泊、河流，天文学家故而称其为太阳系中和地球最相似的“世界”。

　　结果发现，泰坦表面的流体是甲烷，也就是生命体的基础，并且氢气经泰坦的大气层向下流动，最后在地表消失，表明泰坦表面有外星生命消耗掉了这些气体。

　　美国宇航局天体生物学家麦克凯伊说：“如果最终被证实为生命迹象，这将是双重惊喜。因为它不仅证明了外太空有生命存在，同时还意味着与地球生命迥然不同的、并非以水为生的第二种生命形式也存在。”

　　此外，科学家还坚信未来太阳将会膨胀，吞噬地球，但泰坦则会变得暖和而条件宜人。

　　英国大学教授扎尼基则成：“我们相信泰坦有形成生命必需的化学物质。只要光和热足够，生命构造过程就会开始。40亿年之后，当太阳膨胀成一颗红色巨星，泰坦就成为宇宙生命天堂。”