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A Great Conjunction is a conjunction of the planets Jupiter and Saturn.〔 (Orbital Motion Simulation of Jupiter and Saturn ) 〕 The last Great Conjunction took place on May 31, 2000, while the next one will be in late December 2020. Great Conjunctions take place regularly, every 18–20 years, as a result of the combined ~12-year orbital period of Jupiter around the Sun, and Saturn's ~30-year orbital period. The 2000 conjunction fell within mere weeks after both had passed conjunction with the Sun, and it was very difficult to observe without visual aid because the two planets rose only 30–45 minutes before sunrise, depending upon the location of the observer. == Greatest conjunction == Greatest conjunction is a conjunction of Jupiter and Saturn at or near their opposition to the Sun. In this scenario, Jupiter and Saturn will occupy the same position in right ascension on three separate occasions over a period of a few months. Such tripled occurrences are actually known as triple conjunctions. The so-called "Star of Bethlehem" – thought to have appeared c. 7 BC – was theorized to be a greatest conjunction; and some went so far as to assert that it was an occultation of Saturn by Jupiter, with the two planets appearing to merge into a single object as seen from Earth. However such an event did not take place at historic times. At the greatest conjunction in 7 BC, which is said to be the "Star of Bethlehem",〔Michael R. Molnar: The Star of Bethlehem: The Legacy of the Magi, Rutgers University Press, 1999〕 the minimum distance between Jupiter and Saturn was around 1 degree, this is twice the Moon's diameter. The next occultation of Saturn by Jupiter will take place in 7541. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Great conjunction」の詳細全文を読む スポンサード リンク
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