Maybe the Martians are upset that we've introduced ATVs to their planet or maybe it's a slow news week. Regardless, there is no shortage of UFO sightings around the world this week. It's all grist for the mill for the biggest UFO convention of them all, coming up July 1 in Roswell, N.M. Thousands of people watching the annual Snowdown Parade, in Durango, Colo., saw and heard a low-flying aircraft of some sort buzz the parade route twice. In Australia, a municipal worker caught what looks like a flying saucer on his digital camera and three Canadians told their local newspaper about seeing a bright hovering object near Moncton, New Brunswick, last summer. At least the Colorado incident seems easily explained. Most thought the craft was too small to be a piloted aircraft but Terry Fiedler, event coordinator for the Snowdown Light Parade, said, "I saw it go over. I'm guessing it was just somebody coming into town and buzzed the parade because they knew it was going on." Regardless, organizers in Roswell will welcome alternate opinions during the three-day event, which will have a 1940s retro theme, taking the town back to its glory days of alien autopsies and mysteriously dying sheep. Up to 40,000 people are expected at the festival, in which all the townsfolk are encouraged to re-enact the styles and conventions of the 1940s. Astronaut Edgar Mitchell and UFO researcher Stanton Friedman will be the guests of honor.