Wikipedia:Today's featured article/May 7, 2005

A transit of Venus across the Sun takes place when the planet Venus passes directly between the Sun and the Earth, obscuring a small part of the Sun's disc. During a transit, Venus can be seen from the Earth as a small black disc moving across the face of the Sun. A transit is similar to a solar eclipse by the Moon but, although the diameter of Venus is almost four times that of the Moon, Venus appears much smaller because it is much farther away from the Earth. Before modern astronomy, observations of transits of Venus helped scientists measure the distance between the Sun and the Earth using the method of parallax. Transits of Venus are rare and occur in a pattern that repeats every 243 years, with pairs of transits 8 years apart separated by long gaps of 121.5 years and 105.5 years. The first of a pair of transits of Venus took place in 2004 and the next in this pair will occur in June 2012. Before 2004, the last pair of transits of Venus were in December 1874 and December 1882. After 2012, there will be no more transits of Venus until 2117.

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