再见，冥王星 再见,冥王星91

　　翻译：小淳 　　2006年8月底，国际天文学联合会（IAU）正式投票通过决议，将冥王星降级为矮行星。这件年度大事在社会上引起轩然大波，“冥王星降级”更有望成为06年的热门词汇之一。然而，在所有的纷纷扰扰之后，每当你抬头仰望
　　星空时，会否怀念往日太阳系行星家族中最小的弟弟呢？
　　
　　So Long, Little Pluto
　　The News Story
　　
　　Announcer: It’s official. The planet Pluto is no longer. It’s been kicked out of the cosmic[宇宙的] club. Its status has been officially downgraded and the solar system now consists of eight planets rather than nine. The surprise decision by the International Astronomical Union came after a group of astronomers[天文学家] rebelled against[反对] a decision to expand the solar system to 12.
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　　SA注1 staff: Three, two, one
　　The unmanned spacecraft[宇宙飞船] blasted off[发射] earlier this year and it’s heading to the planet Pluto. But the 9th rock from the sun, named after the god of the underworld in Roman mythology[神话], has suffered a bitter blow to its “planethood.
　　IAU speaker: 237 in favor, 157 opposed, 17 abstaining[弃权], so the motion[动议] is carried.
　　Members of the International Astronomical Union have been meeting in Prague and they’re decided this mysterious[神秘的] mass of ice and rock should be stripped of[剥去] its planet status. Professor Mike Cruise is from the University of Birmingham.
　　Cruise: Over the years we’re built better, more sensitive[灵敏的] telescopes[望远镜], much bigger ones, and they can see more objects in the solar system. And so we need to have a good definition of exactly what is a planet and exactly what is a piece of rubble[碎石] left over from when the solar system was formed. And, unfortunately for poor old Pluto, it’s fallen into the rubble rather than being retainedÓ保留] as a planet.
　　Now the celestial[天的] object will be classified in the new category of “dwarf planets.Space scientists also agreed on a new definition of a planet. Professor Cruise outlines the three requirements.
　　Cruise: First of all, they’re got to orbit[绕轨道而行] around the sun and not around any other body. Secondly, they’re got to be big enough to be sort of spherical[球形的] in shape; that is to say the forces of gravity[重力] have got to be strong enough that they’re gathered themselves into a ball, and then the last issue is that they’re got to have cleared the neighborhood around them. They mustn’t be existing with lots of rubble in their close neighborhood.
　　There is one shining star in this cosmic story. Pluto’s demise[让位] is a boon[实惠] for the publishing industry. Every book about the solar system will have to be rewritten.
　　
　　Mike Brown Pluto’s Worst Nightmare
　　
　　Mike Brown brought that long-simmering[用文火煮] issue to a head last summer by discovering an object he nicknamed[昵称] Xena. It’s similar to Pluto only bigger. If Pluto is a planet, as astronomers have classified it for more than 70 years, then we have at least 10 planets in the solar system. If Xena isn’t, we have only eight.
　　Brown’s forte[长处] is finding heavenly bodies, and there’s nobody better at it than he. Since the late 1990s, Brown has been scanning the skies with an old telescope that is too small for exploring distant galaxies[星系] but perfect for the sort of patient, methodical[有系统的] search needed to find dim worlds out beyond Neptune.
　　Brown and his team have already found at least five such bodies. None of them are as big as Pluto, but they all challenge the simple nine-planet model of our solar system that most of us grew up with. And there are undoubtedly[无庸置疑地] more to come. Any number of small planets could still be lurking[潜伏] out there. Brown has, in some way, become the most successful planet hunter in the history of our solar system.
　　
　　A Big Mistake
　　
　　The roots of the problem go back to 1930, when Clyde Tombaugh discovered Pluto. It was classified as the 9th planet. But in recent years, astronomers have found other round worlds out beyond Neptune that are nearly as big as Pluto.
　　Many astronomers have long said that it was a mistake to call Pluto a planet, and many favor demoting it to some new class of object called minor planet or dwarf planet. Some think Pluto should remain a regular planet for cultural and historic reasons. But doing that would logically mean defining the handful of other small round worlds as planets. And experts say dozens if not hundreds more Pluto-like objects remain to be found on the outskirts[外围地区] of our solar system.
　　
　　Mixed Reaction to the Demotion
　　
　　With the vote, toys and models of the original solar system became instantly useless, forcing teachers and publishers to scramble[匆忙] to update[更新] textbooks and lessons used in classrooms for decades.
　　Officials at an American museum have been at the vanguard[先头部队] of the movement to demote Pluto, “We had enormous[巨大的] numbers of telephone calls and I would say things that verged on[接近] hate mail from second-graders - very angry children who said, that have you done? This is the cutest, most Disney-esque注2 of the planets. How could you possibly demote it?’”g
　　But the museum staff are celebrating. They believe Pluto’s new status is more a victory for the astronomical community because it now has a “greatly increased understanding of what a planet is.”
　　The new definition also means students will have to abandon current mnemonic devices[记忆口诀] that helped them remember how the planets are arranged in order from the sun.
　　For example, “Mark’s Very Extravagant[挥霍的] Mother Just Sent Us Ninety Parakeets[长尾小鹦鹉]helped them recall that the order was Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune and Pluto.
　　Perhaps they can now return to the pre-1930 mnemonic: Mary’s Violet[紫罗兰色] Eyes Make John Stay Up[熬夜] Nights.
　　Meanwhile, more than 300 astronomers have signed a petition[请愿书] denouncing[谴责] the IAU’s new planet definition that demotes Pluto. The petition is one more sign that this whole debate is far from over. In another move, the world’s largest group of planetary[行星的] scientists issued a statement suggesting the definition would get worked over between now and the next IAU meeting in 2009. Just as science promises to march forward, so too will all this bickering[争论] and posturing[摆出姿态]. And why not? It’s great fun, some of the best scientific theater[戏剧] of our generation.
　　
　　新闻故事
　　
　　播音员：这是官方消息。冥王星已经不再是行星了，它被踢出了宇宙俱乐部。它已经被正式降级，所以现在的太阳系中再也没有9颗行星，而只剩下8颗。在一群天文学家反对将太阳系的行星数目增加到12颗之后，国际天文学联合会公布了这一惊人的决定。
　　NASA工作人员：三、二、一……
　　就在今年的早些时候，一艘无人驾驶的宇宙飞船升空飞往冥王星。但是作为太阳系的第九颗行星，根据罗马神话中地狱之神的名字命名的冥王星，其“行星地位”却受到了严重的冲击。
　　IAU发言人：237票赞成，157票反对，17票弃权，所以这项决议获得了通过。
　　国际天文学联合会的成员齐聚布拉格，决定剥夺这颗神秘的冰石星球的行星地位。来自伯明翰大学的迈克・克鲁斯教授对此发表了看法。
　　克鲁斯：在过去几年中，我们制造了更加先进、更加灵敏的望远镜，它们体积更大，能看到更多太阳系中的天体。因此我们必须订立更准确的定义，搞清楚何为行星，何为从太阳系形成时留下来的石块。而对可怜的冥王星来说，很不幸，它被降级为石块，无法保持其行星地位。
　　现在这颗天体被归入“矮行星”这个新类别中。太空学家也通过了一个新的行星定义。克鲁斯教授列出了3项要求。
　　克鲁斯：首先，它们要围绕太阳而不是其它天体运转。第二，它们必须大到足以形成近似球体，也就是说，它们自身的重力必须强大到足以让其凝聚成一个球体。最后一点，它们必须清理好自己附近的区域，附近不能存在太多碎石（等小天体）。
　　（不过）在这个宇宙故事中，有一个闪光点。冥王星的降级对于出版业来说是一桩喜事，因为所有关于太阳系的书籍都要重写了。
　　
　　迈克・布朗―冥王星的恶梦
　　
　　去年夏天，迈克・布朗发现了一颗被他昵称为“齐娜”的天体，从而把这个酝酿已久的冥王星问题推到了风尖浪口。这颗星球和冥王星类似―但体积更大。在过去70多年中，天文学家将冥王星归类为行星―如果冥王星是行星，那么太阳系至少有10颗行星。如果齐娜不是行星，那么行星便只有8颗。
　　布朗擅长发现天体，在这方面无人能及。从20世纪90年代后期开始，布朗就用一部旧望远镜观测太空，他的望远镜太小，不足以探索遥远的星系，但很适合用来对海王星之外的阴暗世界进行耐心又有条理的探索。
　　布朗和他的工作团队至少已经发现了5颗这样的天体。它们中没有一颗的体积能比得上冥王星，但它们都对伴随我们成长的那个简单的太阳系“九大行星”之说提出了挑战。而且毫无疑问的是，一定还会出现更多这样的天体。（海王星之外）还可能存在着数之不尽的小行星。从某些意义上而言，布朗成了我们太阳系历史中最成功的行星猎人。
　　
　　一个大错
　　
　　这个问题的根源要回溯到1930年，当时克莱德・汤博发现了冥王星，它被列为第九行星。然而在近年，天文学家发现海王星之外还有其它球状星体，它们的体积几乎与冥王星一般大。
　　很多天文学家早已提出把冥王星称为行星是一个错误，很多人倾向于将它降级到一个新的天体类别，称为小行星或矮行星。而有些人则认为出于文化与历史等原因，冥王星应该继续被视为一般的行星。但如果那么做，从逻辑上就意味着要将一堆其它小星球也定义为行星。专家们指出，我们还将在太阳系的外围发现更多类似于冥王星的天体，这样的星球即使没有几百，也至少有数十颗。
　　
　　众说纷纭话“降级”
　　
　　投票结果出来后，根据原本的太阳系所制作的玩具和模型立即就要报废，教师和出版商也必须赶紧更新他们沿用了几十年的教材和课本。
　　美国一家博物馆的管理人员成了冥王星降级首当其冲的受影响者。“我们收到非常多的电话，还有来自二年级学生的一些近似于攻击邮件的东西―那些孩子非常生气地说：‘你们做了什么？这是最可爱、最有迪斯尼风格的行星。你们怎么可以将它降级？’”
　　而博物馆的员工却为此抚额称庆。他们认为冥王星的降级是天文学界的一个胜利，因为学界现在“对于何为行星的认识大有提高”。
　　这个新的行星定义也意味着学生要抛弃现在这些帮他们记住太阳后面的行星顺序的口诀。
　　例如，“马克那非常挥霍的妈妈刚刚送了我们90只长尾小鹦鹉”，这句话帮助学生记住九大行星的顺序：水星、金星、地球、火星、木星、土星、天王星、海王星和冥王星。
　　或许他们现在要再次使用1930年以前的口诀：玛丽那紫色的眸子使约翰彻夜难眠。
　　与此同时，300多位天文学家已经签署了请愿书，对国际天文学联合会将冥王星“降级”的行星新定义提出谴责。这份请愿书也预示着整场争论远未结束。另一方面，世界上最大的行星学家团体发表了一项声明，建议在从现在到2009年的下一次国际天文学联合会大会之间的时期内再次商榷行星定义。随着科学的稳步前进，所有这些争论不休、表明姿态等行为也会继续下去。但那又何乐而不为呢？这太有趣了，简直就是我们这一代人看过的最出色的科学剧之一。