A group of amateur skywatchers spotted the US Air Force's secret X-37B space plane orbiting the globe.
Air Force spokesman says X37-B space plane is not a "weaponization of space."
The secretive X-37B robot space plane was launched late Thursday. Destination unknown.
Shrouded in secrecy, the Air Force mystery spaceship X-37B will launch tonight in Florida.
In this image provided by NASA, the space shuttle Endeavour is ferried by NASA's Shuttle Carrier Aircraft (SCA) over the Kennedy Space Center in the early morning hours of Sept. 19, 2012, as it departs for California.