A transit of Venus takes place when Venus passes directly between the Sun and the Earth, becoming visible against the solar disk. During a transit, Venus can be seen as a small black circle moving across the face of the Sun.
William Richard Lavender, Jeremiah Horrocks (1618–1641) (1903), Astley Hall Museum and Art Gallery
Diagram from David Rittenhouse's observations of the 1769 transit of Venus
Image: NASA's SDO Satellite Captures First Image of 2012 Venus Transit (Full Disc)
Image: SDO's Ultra high Definition View of 2012 Venus Transit (171 Angstrom Full Disc)
The 2012 transit of Venus, when the planet Venus appeared as a small, dark spot passing across the face of the Sun, began at 22:09 UTC on 5 June 2012, and finished at 04:49 UTC on 6 June. Depending on the position of the observer, the exact times varied by up to ±7 minutes. Transits of Venus are among the rarest of predictable celestial phenomena and occur in pairs. Consecutive transits per pair are spaced 8 years apart, and consecutive pairs occur more than a century apart: The previous transit of Venus took place on 8 June 2004 ; the next pair of transits will occur on 10–11 December 2117 and December 2125 within the 22nd century.
Image of the transit taken by NASA's Solar Dynamics Observatory spacecraft. Venus is in the upper right quadrant
Children in Dili observing the transit of Venus
San Francisco, California, United States Transit of airliner with Venus
Tempe, Arizona, USA 01:54 UTC