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Astronomers have confirmed the first planet outside our solar system in the so-called "habitable zone" -- the area around a star where a planet could exist with liquid water on its surface. |
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The planet, Kepler-22b, was discovered by NASA's Kepler mission. |
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天文學家已確認在我們的太陽系外發現第一顆位於所謂「適居帶」內的行星 —— 適居帶就是指恆星周圍能夠讓行星的表面保有液態水的區域。這顆名為「克卜勒 22b 」的行星是由美國太空總署的克卜勒任務所發現的。 |
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The planet's radius is about 2.4 times that of Earth. |
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It is located about 600 light years away. |
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Its orbital period is shorter than that of Earth: a "year" on Kepler-22b is 290 days instead of 365. |
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這顆行星的半徑約是地球的二點四倍，距離地球約六百光年。其軌道週期比地球短：在克卜勒 22b 行星上，一年為兩百九十天，而不是三百六十五天。 |
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Separate projects this year confirmed two other planets in the habitable zone, but their stars are much cooler than our Sun, and their orbits are much like Venus or Mars, scientists say. |
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Kepler-22b is what is sometimes referred to as a "Goldilocks planet," neither too hot nor too cold to support life. |
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今年的其他計畫也確認發現了另外兩顆位於適居帶的行星，但這兩顆行星繞行的恆星溫度都比我們的太陽低，而且它們的軌道也比較像金星或火星，科學家表示。克卜勒 22b 就是有時人稱的「歌蒂拉行星」，不太熱也不太冷，適合生物生存。 |
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Kepler-22b is 15% closer to its star than we are to the Sun. |
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However, since Kepler-22b's star is dimmer, lower in temperature and smaller than our Sun, researchers' modeling suggests it is a similar temperature to the Earth, said Bill Borucki, Kepler principal investigator at NASA's Ames Research Center. |
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克卜勒 22b 和其恆星的距離比地球與太陽的距離近。不過，由於克卜勒 22b 的恆星亮度比太陽暗，溫度比較低，體積也比較小，因此研究人員的分析模型顯示這顆行星的溫度與地球相當，比爾•博魯奇表示，他是美國太空總署艾姆斯研究中心的克卜勒任務首席研究員。 |
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"If the greenhouse warming were similar on this planet and had a surface, its surface temperature would be something like 72 Fahrenheit, a very pleasant temperature here on Earth." |
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「這顆行星上的溫室效應增溫若與地球相似，而且也有地表，那麼其表面溫度應該是華氏七十二度左右，就地球上而言是非常怡人的溫度。」 |
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The warmer a planet, the more evaporation of water there would be, Borucki said. |
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A planet can't have a surface temperature that's very hot without losing all of the surface water. |
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一顆行星的溫度愈高，水分就愈容易蒸發，博魯奇說。行星不可能表面溫度高而不喪失所有的表面水。 |
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The Kepler mission reported in February that it had found 54 planet candidates in the habitable zone. |
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Kepler-22b is the first of these to be confirmed, and those results will be published in The Astrophysical Journal. |
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There are still 48 potential planets from that batch. |
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克卜勒任務在二月報告指稱發現了五十四顆位於適居帶的候選行星。克卜勒 22b 是最早確認的一顆，這些發現結果也將刊登於《天文物理期刊》。那批行星中還有四十八顆行星可能符合歌蒂拉行星。 |
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Researchers find planets by examining the brightness of stars as a function of time; brightness drops when a potential planet crosses the star. |
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Three transits are required for a planet confirmation. |
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The period of the transit of Kepler-22b was 7.4 hours. |
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It did not appear to give off its own light, indicating it is a planet and not a star. |
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研究人員發現行星的方式，是把恆星的亮度當成時間函數加以檢驗。可能是行星的星體一旦經過恆星前方，恆星的亮度就會降低。一顆星體必須經過三次凌日，才能確認為行星。克卜勒 22b 的凌日週期為七點四小時，而且本身似乎不會發光，可見得這顆星體是行星而不是恆星。 |
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