M. Night Shyamalan famously filmed his 2002 alien invasion flick Signs in Bucks County -- and tomorrow, UFO enthusisasts will flock there, a location they say is increasingly becoming a hotspot for odd aerial phenomena.

Last year, the county had over 100 sightings, more than the entire state did the year before, said John Ventre, director of the Pennsylvania Mutual UFO Network and one of the organizers of the conference.

Overall, 312 reports were filed in Pennsylvania - 225 in the second half of the year, he said.

So far, Ventre said his group, which has 133 members and 21 investigators, has been able to find explanations for about 20 percent of the cases as hoaxes or sightings of identifiable aircraft, satellites or planets.

Of course, that doesn't mean the remaining 80 percent involve alien spacecraft.

Alternative explanations include everything from optical illusions to weird weather phenomena, from experimental military aircraft to contraptions launched by pranksters.

Extra-terrestrials, though, are on the agenda at the conference, scheduled for noon to 5 pm at the Newtown campus of Bucks County Community College.

Besides Ventre and Bill Birnes of the History Channel's UFO Hunters, one of the main speakers will be Temple University professor David Jacobs, author of UFOs and Abductions and The Threat: Revealing the Secret Alien Agenda.

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