The Search for Extraterrestrial Intelligence (SETI) project at the University of California is just one of countless endeavors continuously scanning optical, infrared and radio frequencies for signals from distant civilizations in space. Since 1999, more than five million computer users have run the SETI@Home program that recycles unused computing power to analyze data collected from radio telescopes. The International Academy of Astronautics already has established a standing committee to advise political leaders what to do if someone discovers a signal from ET. A confirmed message from another civilization would utterly transform society, taking the planet on an unprecedented journey into the unknown.