Venus (black dot) is silhouetted as it o
Venus (black dot) is silhouetted as it orbits between the Sun and the Earth during the transit of Venus seen from Bangkok on June 6, 2012. Astronomers around the world trained their telescopes on the skies to watch Venus pass in front of the Sun, a once-in-a-lifetime event that will not be seen for another 105 years. AFP PHOTO / PORNCHAI KITTIWONGSAKUL (Photo credit should read PORNCHAI KITTIWONGSAKUL/AFP/GettyImages)