June 8, 2004: The transit of Venus; Venus transits the Sun.
This was the first transit of Venus since the last one in 1882.
Transits of Venus occur in a pattern that generally repeats every 243 years, with pairs of transits eight years apart separated by long gaps of 121.5 years and 105.5 years. The most recent transit of Venus was on 5 and 6 June 2012, and was the last Venus transit of the 21st century. The previous pair of transits were in 1874 and 1882, and the next transits will take place in 2117 and 2125.
The discovery of the atmosphere on Venus is attributed to the Russian Academician Mikhail Lomonosov on the basis of his observation of the transit of Venus of 1761 from the Imperial Academy of Sciences of St. Petersburg.
2004 transit of Venus, (c) Fred Espenak: