单词 | thuban |
释义 | ThubanThuban(thew -băn) (α Dra) A white giant in the constellation Draco that was the pole star about 2700 bc when it lay 10′ from the north celestial pole. Now of magnitude 3.6, its brightness has probably decreased in the past few hundred years. Because of precession, it will approach the pole again in about 21,000 years' time. Despite its designation as Alpha (α), it is in fact the fourth brightest star in the constellation. Spectral type: A0 III; distance: 95 pc.Thuban[′thü‚ban] |
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