所以一个行星上要有足够的温度，那么这个行星距恒星的距离就得比它距离太阳的距离近，这样，这个行星上才能具备合适的温度，维持一定的光照和液态水。
So to have the same temperature, a planet needs to be much closer to that star than it would be from the sun, where you'd have a temperature where you might have light and liquid water.
来自华盛顿·卡内基学院的保罗·巴特勒说：“由于这颗行星距临近恒星的距离恰好合适，所以这个星球上的温度既不太热也不太冷。”这正好使液态水能很好的保存下来。
"The planet has to be the right distance from the star so it's not too hot and not too cold that liquid water can exist," says Paul Butler of the Carnegie Institution of Washington.
直到目前，对于CCD观测者唯一合适可用的星表是GSC(哈勃空间望远镜的引导星参考星表)，它包含1.8亿个目标(恒星和星系)。
Until quite recently, the only useable catalogue for CCD observers was the Hubble Space Telescope's Guide star catalogue (GSC), that contains about 18 million objects (stars and galaxies).
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