A look at encounters astronauts believe to have had with aliens.
Some believe that extraterrestrials cause atmospheric light-shows.
Whether extraterrestrials already live on Earth; an alien enemy may orchestrate a doomsday scenario.
The world's military forces have come face-to-face with thousands of unidentified objects.
UFOs may endanger commercial airliners; mid-air abductions; near-disasters caused by unseen enemies.
At times, UFOs appear in the sky faster than authorities can track them.
Millions of people may be alien abductees without being aware of it.
Both aliens and Earthlings may secretly possess advanced antigravity technology.