FILE - A sign directs travelers to the start of the "1947 UFO Crash Site Tours" in Roswell, N.M., June 10, 1997. World UFO Day is being celebrated amid a surge in sightings and government studies on unidentified flying objects. Its date of July 2nd has its roots in the so-called Roswell incident on July 2, 1947. (AP Photo/Eric Draper, File)