Vulcan? 火神星?

 焖黄鳝 2011-01-16
A new planet


Time to start giving extrasolar planets proper names

ASTRONOMERS are a curious bunch. Some like to name things. Others prefer numbers and letters. Those who study the solar system fall into the former camp. Every planet, asteroid, moon, mountain and crater has its name. Mankind’s mythologies have been ransacked so thoroughly that the need to identify each orbiting rock has resulted in such curiosities as Zappafrank, Lennon, McCartney and even Bagehot. Those who study other planetary systems have been more restrained. Planets orbiting stars beyond the sun are labelled merely with the name of the star and a suffix letter. Even if planets and moons were found round Alpha Centauri, as envisaged by the writers of “Avatar”, they would not get glorious monikers like Polyphemus and Pandora. They would just be letters—and lower-case ones, to boot.
天文学家们是一群奇妙之人,有些喜欢命名,有些喜欢数字和字母。研究太阳系的天文学家属于前一个阵营。由于每一行星、小行星、月亮、山岳及火山口都有自己的名字,人类的神话故事已被倾囊搜遍,结果那些需要甄别的岩石行星只好被冠上“Zappafrank”、列农(Lennon)、麦卡特尼(McCartney)、甚至巴杰特(Bagehot)这类离奇的名字。研究其它行星系统的科学家则受到更多的命名限制。属于太阳以外恒星的行星们仅仅得到该恒星的名称,外加一个后缀字母。即使它们围着半人马座(Alpha Centauri)团团转,也得不到像《阿凡达》中“波吕斐摩斯”和“潘多拉”( Polyphemus and Pandora) 如此星光灿烂的绰号。它们只是一些附属的字母,而且还是小写的字母。

That is sad. Though the nominative diarrhoea of the solar system may have gone a little far, a well-chosen name is both picturesque and memorable. Perhaps, therefore, it is time to change the convention and give such a name to an extrasolar planet. And an ideal candidate has just turned up—one that matches one of astronomy’s own myths: the legendary, non-existent planet Vulcan.

Kepler-10b, to give this planet’s current name, is the latest discovery by Kepler, an American spacecraft. The new object, whose existence was announced on January 10th at a meeting of the American Astronomical Society, in Seattle, is causing excitement because it is the smallest extrasolar planet yet discovered. Its diameter is a mere 1.4 times that of Earth, though it weighs 4.6 terrestrial masses. What makes it Vulcanlike, though, is that it circles its star, Kepler-10, once every 20 hours, in an orbit a twentieth the size of Mercury’s.

Astronomers of the 19th century spent decades searching for a planet within Mercury’s orbit, and confidently named it after the fireloving Roman god of smiths even before they found it. Their reason for thinking Vulcan existed was that Mercury’s orbit behaved as if a more inward planet was tugging on it.

That discrepancy was eventually explained by Einstein as a relativistic effect of the sun’s gravity, and the search for Vulcan petered out. Kepler-10b, however, has some curious parallels with the solar system’s non-existent innermost planet. The first is its location so close to its parent star. Second, despite its size, it is quite heavy. That would have been a useful characteristic in the original Vulcan, had it been real. Third, its high mass probably means it is made of iron, an appropriate material for a planet named after a divine smith. And fourth, it was found in exactly the way the hunt for Vulcan proceeded—by noting the slight dip in light from its parent star caused when it passed in front of that star.
这种差别最终被爱因斯坦以太阳引力相对效应解释清楚了,因此对“火神星”的搜索也逐渐淡失。然而对Kepler -10b的好奇与当年搜索太阳系内不存在的近核心行星颇有相似之处。首先是新行星的位置非常接近其所属恒星,其次,它虽小却相当沉重。如果当年找到了火神星的话,那颗星也会具备这个有用的特征。第三,新星的高重量值可能意味着它由铁组成,正好适合用火神并且是一名铁匠来命名。第四,它被发现的方法正如当年寻找火神星一样——当它在其"父”恒星前面飞过时,导致恒星亮度微微黯淡的这个关键被捕捉到了。

Numbers have their place in science, of course. Indeed, the subject is founded on them. But the driving force behind a lot of scientific activity is far more romantic than many non-scientists appreciate—and the search for other Earths, with their tantalising promise of other life forms, is about as romantic as it gets.

Keep numbers, then, in their proper place—for counting things. For describing them, names are better. And where better to start the process of naming the unfolding atlas of new planets than with the magical smith who was Venus’s husband and cuckolded by Mars?

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