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今天是天文学家发现海王星的一周年——海王星的一年。 At an average distance of 2.8 billion miles (4.5 billion kilometers) from the sun, Neptune takes about 165 Earth years to finish a single orbit. 海王星距离太阳平均28亿英里（相当于45亿公里），绕太阳转一圈需要165个地球年。 That means July 12 marks the planet's first complete orbit around the sun since astronomers first observed it in 1846. The planet officially reaches this milestone at 22:27 UT. 那就意味着7月12日是海王星自年第一次被天文学家观测到以来第一次完成绕太阳的轨道运行。格林威治时间22点27分，海王星正式完成这一里程。 How Galileo Missed the Mark 伽利略如何错过了这个发现 Technically, Neptune's existence was mathematically predicted years earlier, based on the gravitational effect the ice giant planet was having on neighboring Uranus. 从学术上来说，更早之前，基于这颗巨大的冰球对邻近的天王星的引力作用，人们就已经精确地预测到海王星的存在。 By looking for discrepancies in Uranus's orbit, Englishman John Couch Adams and Frenchman Urbain Le Verrier each independently calculated the unseen world's mass and position. 在寻找天王星轨道的差异时，英国人约翰·考奇·亚当斯和法国人于尔班·勒威耶分别独立计算着这个未知世界的质量和位置。 But Neptune's existence wasn't confirmed until September 23, 1846, when German astronomer Johann Galle used a telescope to search the predicted location in the sky and spotted a tiny blue-green disk. The planet was eventually named Neptune, after the Roman god of the sea. 但是，直到1846年9月23日，德国天文学家约翰·加勒用望远镜在天空预计的位置搜寻并发现了一个微小的蓝绿色圆盘，海王星的存在才得到证实。这颗行星最终以罗马神话中的海神命名，称为海王星。 Ironically, Galileo Galilei spotted Neptune more than 200 years earlier but wrongly assumed the planet was just a star." He observed it and he thought it moved relative to background stars, but it became cloudy and he was unable to observe it further," said Rocky Alvey, director of the Vanderbilt Dyer Observatory in Brentwood, Tennessee. "If it hadn't been for clouds, Galileo may have been the discoverer of Neptune." 具有讽刺意味的是，伽利略早在200多年前就发现了海王星，却误认为这只是一颗恒星。“伽利略看到了这颗行星，并且辨认出它存在相对于恒星背景的移动。但是此时天气开始有云了，他无法再做进一步的观察，”洛克·阿尔维说道，他是田纳西州布伦特伍德的范德比尔戴特尔天文台的主管。“如果不是被云遮挡，伽利略可能已成为海王星的发现者。” Neptune Mysteriously Stormy 海王星的神秘风暴 The closest approach to Neptune by a spacecraft occurred in 1989, when NASA's Voyager 2 passed within 3,000 miles (4,950 kilometers) of the planet's north pole. 人类与海王星最近距离的一次接触发生在1989年，当时美国宇航局的旅行者2号探测器从海王星北极上空3000英里（4950公里）经过。 But even with more than a century and a half of observations, many unresolved questions remain about the farthest planet from the sun. 不过，即使经过了一个半世纪的观测，这个距离太阳最远的行星，仍有许多尚未解决的问题。 For example, it's still unclear how Neptune is generating the heat needed to power the changes astronomers have observed in its atmosphere. 比如，天文学家们目前仍不清楚，海王星是如何产生热量为变幻无常的大气提供所需的动力。 "It only gets 0.1 percent as much sunlight as Earth, but Neptune has storms and its appearance changes over time," said Erich Karkoschka, an astronomer at the University of Arizona. “海王星获得的日照是地球的0.1%，但是海王星存在着风暴，以及不断变化的大气形态，”亚利桑那大学的天文学家埃里克·卡尔科施卡说。 Neptune was much darker in the 1970s and '80s than it is now, and large dark spots corresponding to giant storms have previously been observed in the planet's atmosphere by Voyager 2 and the Hubble Space Telescope. 在20世纪70年代和80年代，海王星比现在更加黑暗，旅行者2号和哈勃望远镜曾观测到巨型风暴的大黑斑。 "If we can understand how a planet with so little sunlight can have a very active atmosphere," Karkoschka said, "then I think we'll understand Earth's atmosphere and the planetary atmospheres of the more than 500 exoplanets around other stars better." “如果我们能弄清楚一个日照如此之少的星球是维持这样一个活跃的大气变化，”卡尔科施卡说道，“那么我想我们会更好的了解地球和其它已发现的500多个太阳系外行星的大气模式。” Find Neptune in the July Sky 在七月的天空寻找海王星 Although Neptune is not among the planets visible to the naked eye, early birds with telescopes in the United States can spot Neptune this month—if you know where to look. 虽然海王星不属于肉眼可见的行星，这个月在美国早起的人们便可以用望远镜看到海王星——如果你知道往哪里看的话。 Through August the faint planet will appear just above the horizon near the constellation Aquarius in predawn skies. 到了八月份，这颗微弱的星球将会出现在黎明前的天空，位于宝瓶座附近的地平线上。 "Prime viewing time is early morning, from midnight to 4 a.m." central time, the Vanderbilt Dyer Observatory's Alvey said. "It's just beyond the visual limit, so ... you'll be able to spot Neptune with a small telescope or even just a pair of binoculars." “最佳观看时间是清晨，从午夜到凌晨4点。”中央标准时间，范德比尔特戴尔天文台的阿尔维说。“这只是超出了肉眼的视觉极限而已，因此……你可以用小型望远镜，甚至是一副双筒望远镜便可以看见海王星。”
从海王星最大的卫星崔坦上观察海王星
海王星的大黑斑
海王星的云 | 
发表于 2011-7-16 10:44
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