"It wasn't just one event, there were many events across the state for more than 12 hours," said Dr. Lynne Kitei with the Phoenix Lights Network.
Kitei said the event remains unexplained even though though the military tried explain it.
"The military tried to explain it as flares five months after the event," she said. "Some people saw the mile-wide craft glide over their heads at rooftop level silently. Some saw it take off at lightning speed. Some people saw orbs detach from the main object."
One witness from Prescott who wishes to be known only as J.R. said he watched a boomerang-shaped object glide over Granite Mountain, and it was at least a mile wide. He says there's no way it was from this planet.
"We don't have anything that big," he said. "It was totally silent. I've never seen anything even close to the colors from the exhaust that propelled that thing. It was as big as downtown Prescott and completely blocked out the stars."
Kitei said a program is scheduled for Sunday at 1 p.m. at the Scottsdale Harkins Shea Cinema to celebrate the 17th anniversary of the historic and still unexplained mass UFO sighting. For more information, visit http://www.thephoenixlights.net/.