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3.Is Life Existing Somewhere Else Besides Earth?
3.地球之外有生命吗？
Since early times, people have beenfascinated with the idea of life existing somewhere else besides earth. Untilrecently, scientists believed that life on other planets was just a hopefuldream. But now they are beginning to locate places where life could form.
很久以来，人们就被地球以外存在生命的观点强烈地吸引。直到近期，科学家们都坚信外星生命的想法只不过是个有希望的梦想。但是现在他们开始定位外星生命形成的位置。
In 1997, they saw evidence of planets nearother stars like the sun. But scientists now think that life could be evennearer in our own solar system. One place scientists are studying very closelyis Europa, a moon of Jupiter.
在1997年，他们在像太阳这类其他恒星的行星上发现了证据。可是，现在科学家认为外星生命甚至更接近我们，就存在于我们太阳系中。科学家们正在仔细研究的这个地方是欧罗巴，是木星的卫星。
Space probes have provided evidence thatEuropa has a large ocean under its surface. The probes have also madescientists think that under its surface Europa has a rocky core giving offvolcanic heat. Water and heat from volcanic activity are two basic conditionsneeded for life to form.
太空探索提供的证据表明在欧罗巴的表层下蕴藏着一个巨大的海洋。太空探索还使科学家们相信在欧罗巴的表层下有一个岩层核心，释放出火山般的热量。火山活动的水和热是生命形式所需的两个基本条件。
A third is certain basic chemicals such ascarbon, oxygen and nitrogen. Scientists believe there might be such chemicalslie at the bottom of Europa's ocean.They may have already created life or maybe about to. You may wonder if light is also needed for life to form. Untilrecently, scientists thought that light was essential.
第三个条件是某些基本的化学元素，如：碳、氧、氮。科学家相信在欧罗巴的海底可能存在这些物质。它们或许已经创造了生命，也许将来会产生生命。你或许想知道光对于生命的形成是否必要。直到最近，他们都认为光是必须的。
But now, places have been found on earththat are in total blackness such as caves several miles beneath the surface.And bacteria, primitive forms of life have been seen there. So the lack oflight in Europa's sub-surface ocean doesn't automatically rule out lifeforming.
但是，现在地球上完全黑暗的地方也有生命，如在地表下数公里的洞穴中。生命原始形式的细菌就存在于那儿。因此，在欧罗巴表层以下缺少阳光的海洋中无法自动排除生命存在的可能。
