U.S. Map of the Top UFO Hotspots

To find out, PM consulted the Center for UFO Studies, which maintains a database of sightings reported from 1947 to 2005. Illinois-based CUFOS gathers data from UFO reporting groups and public records, including Project Blue Book. (If several people report the same sighting, CUFOS registers it as a single event.) For a broad comparison, we ranked both metropolitan and more sparsely settled counties.

Why did these 10 top the list? Perhaps because some are close to military training zones called Special Use Airspace. An uptick in sightings over Santa Rosa County, Fla., could stem from the presence of an air wing that tests every fighter, bomber, unmanned aerial vehicle and ­weapon in the Air Force inventory. Military refueling lanes crisscross the nation, and lights from air tankers and warplanes flying at night in close formation could appear as triangles of light from the ground.

Psychology may also play a role. Westmoreland County, Pa. (pop. 362,326), which records more sightings than the metro Houston area (pop. 3.9 million), includes Kecksburg, the location of a reputed 1965 UFO crash. Residents there may be more likely to report strange lights to a UFO group.

What to Do Before You Report a UFO

So you've just seen some eerie lights in the sky, glowing orbs that moved in strange ways. This is a UFO report waiting to happen. But before you go tell all to the MUFON it could help to check what's in the sky in your area. Here is your 3-step checklist. –Joe Pappalardo

1. Is it Venus?
February was a great time to watch for Venus because it was at its brightest in the evening twilight sky. "Venus will be coming closer still to Earth," the dedicated skywatchers at www.earthsky.org wrote. "But it will be showing us less and less of its lighted hemisphere as it prepares to pass between us and the sun. So now is the time of maximum brilliance."

Earthsky.org and Space.com have updates on prominent celestial happenings that might explain your UFO. If you feel like spending money, programs like Starry Night are available for download.

2. Is it a military exercise?
There's no way to tell when and where the military is conducting flights, right? Wrong.

The FAA needs to tell pilots when military airspace is being used to keep collisions from happening. This website tracks which sections of "special use airspace" will be used for military flights. This includes military operations areas and aerial refueling Missions. For a list of airbases, airports and special use airspace, also see seeandavoid.org, a website established by the Defense Safety Oversight Council to deter midair collisions.

3. Is it an Earthling's spaceship?
Satellites and spacecraft can be tracked via NASA's website. They use data from flight centers to track satellites and spacecraft. There is a text-based version and an 300 K applet.