The planet Venus passes in front of the setting sun behind Colorado National Monument on June 5, 2012. The event known as a “transit” is the last one for Venus this century. The brightest planet, as seen from Earth, took nearly seven hours to traverse the face of the sun. From many vantage points, the transit was in progress at sunrise or sunset. During the transit, Venus appeared in silhouette as a small, dark dot moving in front of the solar disk. The rare astronomical event won’t happen again until Dec. 11, 2117. A transit of Mercury, the planet closest to the sun, will take place on May 9, 2016.