[E483]How to find exoplanets|经济学人
本文音频及原文摘自杂志The Economist 2016年第35期，Science and Technology版块。
How to find exoplanets
Two ways to detect what you cannot see
Aug 27th 2016
A PLANET orbiting a star tugs[1] it gently this way and that[2], so it oscillates[3] between moving towards Earth and away from it. The velocities[速度] involved are tiny: for Proxima Centauri[4] about two metres per second, a brisk walk[轻快行进;快步走]. Nevertheless, the effect on the star’s spectrum[光谱;频谱] can be measured from the ground. When a star is approaching Earth, its light is slightly bluer; when away, slightly redder. For this method, the plane of the planet’s orbit need not be aligned with[与…对准] Earth.
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The transit technique, by contrast, requires that it is, so that the planet passes between Earth and its parent star[母恒星] every orbit. When that happens, the parent star’s light will dim[暗淡的;昏暗的] accordingly. Transiting was used with great success by Kepler, an American space telescope which detected well over 1,000 distant planets earlier this decade. Statistical analysis[统计分析] of that sample suggests many—possibly all—red dwarfs[5] have rocky planets[岩态行星], and that they are likely to crop up[突然发生;出现] quite frequently in a red dwarf’s habitable zone[宜居带]. Since red dwarfs are the commonest[最常见的] stars, the most likely place to find an Earthlike planet is in orbit around one.
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注释
[1]tug [tʌg]
to pull something quickly and usually with a lot of force （用力）拉，拖，拽
Tom tugged at his mother's arm.
汤姆拽着妈妈的胳膊。
[2]this way and that：in many different directions 忽左忽右；上下左右地；下不了决心；踌躇不决
The rabbit ran this way and that, trying not to get caught.
[3]oscillate ['ɒsɪleɪt]
to move repeatedly from one position to another 来回摆动；振动；振荡
The needle on the dial oscillated between full and empty.
刻度盘上的指针在“满”和“空”之间来回摆动。
[4]Proxima Centauri 比邻星(毗邻星)是半人马座α三合星的第三颗星，依拜耳命名法也称为半人马座α星C。它是离太阳系最近的一颗恒星（4.22光年）。
[5]red dwarf 红矮星是指表面温度低、颜色偏红的矮星，尤指主序星中比较“冷”的M型及K型恒星，这些恒星质量在0.8个太阳质量以下，105个木星质量以上，表面温度为2,500至5,000K。除太阳外最接近地球的恒星比邻星(Proxima Centauri)便是一颗红矮星。
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相关新闻
北京时间8月25日凌晨消息，就在刚刚，欧洲南方天文台（ESO）发布了一项声明，确认了此前已经在坊间流传多时的一个消息：科学家们在距离太阳系最近的半人马座比邻星周围发现了一颗岩石系外行星，并且其与比邻星之间的距离适当，因而处于所谓“宜居带”范围内，这就意味着其地表有可能允许水体以液态形式存在，这就意味着这颗行星表面有可能存在适宜生命居住的环境条件。在比邻星周围发现可能存在宜居条件，并让人猜想可能存在生命的系外行星。
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以上言论不代表本人立场。
原文摘自The economist，仅外语学习之用。
其中生词解释来源于Cambridge Dictionaries
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