Morning Scepticism: UFOs

There are a large group of people who are dedicated to looking into the night sky, with anything from binoculars to good sized telescopes. These amateur astronomers are dedicated star gazers, who know quite a bit about what to expect to see in the sky. Yet UFO sightings are seldom seen by amateur astronomers, but by people who don't know much about what to look for. How are we to conclude that alien sightings are anything but an expression of ignorance in the face of the unknown?