Venus passing across the Sun in 2004. credit: Astroblue
On 5 and 6 June 2012, Venus passed directly between the Sun and the Earth. This extremely rare event had only been observed with telescopes on six previous occasions. After 2012, the next transit will be in 2117.
Astronomers, many of whom were associated with the Royal Society, used previous transits to calculate the distance between the Earth and the Sun. The map below shows some of the places where scientists travelled in order to take their measurements.
Past transits: 1639 | 1761 | 1769 | 1874 | 1882 | 2004