What in the world are UFOs? Throughout history there have been many reported sightings of strange objects in the sky, and some that even landed on the earth. Could it be that these mysterious balls of light, ovals, and disks, are truly visitors from another planet? Or is it possible that there are more earthly explanations for these close encounters? this book explores all the mysteries of UFOs -- from science to science fiction -- and tries to answer the question that has plagued earthlings for centuries.