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 4 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.

Read the rest of this article: http://en.wikipedia.org/wiki/Transit_of_Venus

_______________________________ Today's selected anniversaries:

1824: Ludwig van Beethoven's Symphony No. 9 in D minor premiered in Vienna. (http://en.wikipedia.org/wiki/Symphony_No._9_%28Beethoven%29)

1915: World War I: The ocean liner RMS Lusitania was torpedoed and sunk by the German submarine Unterseeboot 20, killing 1,198 on board. (http://en.wikipedia.org/wiki/RMS_Lusitania)

1920: Polish-Soviet War: Polish-Ukrainian troops led by Józef Pi?sudski and Edward Rydz-?mig?y carried out the Kiev Offensive to capture Kyiv, Ukraine. (http://en.wikipedia.org/wiki/Kiev_Offensive_%281920%29)

1945: End of World War II in Europe: In Reims, France, General Alfred Jodl signed and submitted the capitulation documents to the Allies on behalf of Reichspräsident Karl Dönitz. (http://en.wikipedia.org/wiki/Reims)

1992: The Space Shuttle Endeavour was launched for its first mission. (http://en.wikipedia.org/wiki/Space_Shuttle_Endeavour)

_____________________ Wikiquote of the day:

"Where men are the most sure and arrogant, they are commonly the most mistaken, and have there given reins to passion, without that proper deliberation and suspense, which can alone secure them from the grossest absurdities." -- David Hume (http://en.wikiquote.org/wiki/David_Hume)