Transit of Venus
A transit of Venus takes place when Venus passes directly between the Sun and the Earth (or any other superior planet), becoming visible against (and hence obscuring a small portion of) the solar disk. During a transit, Venus is visible as a small black circle moving across the face of the Sun.
This article is about the astronomical phenomenon. For other uses, see Transit of Venus (disambiguation).
Transits of Venus reoccur periodically. A pair of transits takes place eight years apart in December (Gregorian calendar) followed by a gap of 121.5 years, before another pair occurs eight years apart in June, followed by another gap, of 105.5 years. The dates advance by about 2 days per 243 year cycle. The periodicity is a reflection of the fact that the orbital periods of Earth and Venus are close to 8:13 and 243:395 commensurabilities. The last pairs of transits occurred on 8 June 2004 and 5/6 June 2012. The next pair of transits will occur on 10–11 December 2117 and 8 December 2125.
Transits of Venus were in the past used to determine the size of the Solar System. The 2012 transit has provided research opportunities, particularly in the refinement of techniques to be used in the search for exoplanets.
Grazing and simultaneous transits[edit]
Sometimes Venus only grazes the Sun during a transit. In this case it is possible that in some areas of the Earth a full transit can be seen while in other regions there is only a partial transit (no second or third contact). The last transit of this type was on 6 December 1631, and the next such transit will occur on 13 December 2611. It is also possible that a transit of Venus can be seen in some parts of the world as a partial transit, while in others Venus misses the Sun. Such a transit last occurred on 19 November 541 BC, and the next transit of this type will occur on 14 December 2854.[2] These effects are due to parallax, since the size of the Earth affords different points of view with slightly different lines of sight to Venus and the Sun. It can be demonstrated by closing an eye and holding a finger in front of a smaller more distant object; when the viewer opens the other eye and closes the first, the finger will no longer be in front of the object.
The simultaneous occurrence of transits of Mercury and Venus does occur, but extremely infrequently. Such an event last occurred on 22 September 373,173 BC and will next occur on 26 July 69,163,[34] and again on 29 March 224,504.[35] The simultaneous occurrence of a solar eclipse and a transit of Venus is currently possible, but very rare. The next solar eclipse occurring during a transit of Venus will be on 5 April 15,232.[36]
In Popular Culture[edit]
The Canadian rock band Three Days Grace titled their fourth studio album _Transit of Venus_ and announced the album title and release date on June 5, 2012, the date of the last transit of Venus. The album’s first song, “Sign of the Times”, references the transit in the lyric “Venus is passing by”.
The Transit of Venus March was written by John Philip Sousa in 1883 to commemorate the 1882 transit.