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A transit of Mercury across the Sun takes place when the planet Mercury comes between the Sun and the Earth, and Mercury is seen as a small black dot moving across the face of the Sun. Transits of Mercury with respect to Earth are much more frequent than transits of Venus, with about 13 or 14 per century, in part because Mercury is closer to the Sun and orbits it more rapidly. Transits of Mercury occur in May or November. The last three transits occurred in 1999, 2003 and 2006; the next will occur in 2016. On June 3, 2014, the ''Curiosity'' rover on the planet Mars observed the planet Mercury transiting the Sun, marking the first time a planetary transit has been observed from a celestial body besides Earth. == Occurrence of transits == Transits of Mercury can happen in May or November with May transits being about half as frequent as November transits.〔(【引用サイトリンク】 Seven Century Catalog of Mercury Transits: 1601 CE to 2300 CE )〕 They currently occur within a few days either side of May 8 and November 10. The interval between one November transit and the next November transit may be 7, 13, or 33 years; the interval between one May transit and the next May transit may be 13 or 33 years. May transits are less frequent than November transits because during a May transit, Mercury is near aphelion whereas during a November transit, it is near perihelion. Perihelion transits occur more frequently due to two effects: firstly, Mercury moves faster in its orbit at perihelion and can reach the transit node more quickly, and secondly at perihelion Mercury is closer to the Sun and so has less parallax. During May transits Mercury has an angular diameter of 12"〔 and these transits take place at the descending node〔(【引用サイトリンク】 Seven Century Catalog of Mercury Transits: 1601 CE to 2300 CE )〕 of Mercury's orbit. During November transits Mercury has an angular diameter of 10"〔 and these transits occur at the ascending node.〔 Transits of Mercury are gradually drifting later in the year; before 1585 they occurred in April and October. 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「Transit of Mercury」の詳細全文を読む スポンサード リンク
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