PARIS – The saucer-shaped object is said to have touched down in the south of France and then zoomed off. It left behind scorch marks and that haunting age-old question: Are we alone?
This is just one of the cases from France's secret "X-Files" — some 100,000 documents on supposed UFOs and sightings of other unexplained phenomena that the French space agency is publishing on the Internet.
France is the first country to put its entire weird sightings archive online, said Jacques Patenet, who heads the space agency's UFO cell — the Group for Study and Information on Unidentified Aerospace Phenomena.
Their oldest recorded sighting dates from 1937, Patenet told The Associated Press in an interview Friday. The first batch of archives went up on the agency's Web site this week, drawing a server-busting wave of traffic.
"The Web site exploded in two hours. We suspected that there was a certain amount of interest, but not to this extent," Patenet said.
The archive includes police and expert reports, witness sketches (some are childlike doodlings), maps, photos and video and audio recordings. In all, the archive has some 1,650 cases on record and about 6,000 witness accounts.
• Click here to visit FOXNews.com's Space Center.
The space agency, known by its French initials CNES, said it is making them public to draw the scientific community's attention to unexplained cases and because their secrecy generated suspicions that officials were hiding something.
"There's always this impression of plots, of secrets, of wanting to hide things," Patenet said. "The great danger would be to leave the field open to sects and charlatans."
He said many cases were unexplained lights in the sky. "Only 20 to 30" could be classified as "Objet Volant Non Identifie" — UFOs that appeared to be physical objects, leaving "marks on the ground, radar images," he said.
Even Charles de Gaulle, France's wartime hero who became president, got the UFO bug.
"In 1954, there was a wave of sightings of phenomena in France, and it went up to the highest levels of state. Gen. de Gaulle himself assigned ... an aide and told him, 'Look into this for me, study it to see if something needs to be done,'" Patenet said.
That year, there were hundreds of sightings over several months, but generally there are 50 to 100 reported each year.
Only 9 percent of France's strange phenomena have been fully explained, the agency said. Experts found likely reasons for another 33 percent, and 30 percent could not be identified for lack of information.
Other cases were impossible to crack. The most baffling were labeled "Class D aerospace phenomena" — which the agency defines as "inexplicable despite precise testimonies and the (good) quality of material information gathered." Some 28 percent of sightings fall into this category.
Patenet singled out the January 1981 case of the saucer-shaped object that a witness said he saw land in Trans-en-Provence, a village inland from the French Riviera.
Some 8 feet across, the zinc-colored object made a whistling noise as it landed. The witness later drew a picture: It resembled a wok with a lid and legs.
"The machine stayed a few seconds on the ground and then left very quickly but it left marks that were analyzed and allowed us to determine that the ground had been heated up, that the object must have weighed several hundred kilos (pounds), and that surrounding plants underwent biological changes," said Patenet.
"So something really happened. It really defies analysis," he said.
The agency said everything in the archive would be published, except for psychological reports about witnesses and their names.
Most of the time, witnesses were sincere about what they saw, Patenet said.
"Very few look for publicity because they fear most of all that they will not be taken seriously."
Still, there were frauds.
In 1979, in Cergy-Pontoise outside Paris, a man showed up at a police station claiming his friend had been abducted by a UFO — a bright light that appeared on the road and swallowed up his car. Several days later, the man purportedly reappeared in a field, emerging out of a sphere of light.
Investigators went so far as to test the man's blood for signs that he had recently experienced weightlessness — and they found none. The agency labeled it a hoax.
Some cases took years to unravel. In 1985, two farmers near the Atlantic coastal city of Royan saw a burning object drop into a field nearby.
Experts initially concluded that it was part of the propulsion device of a recently launched satellite. Eventually they realized it was a piece of German World War II ordnance that spontaneously exploded four decades after the war.
Among the unexplained cases, one of the most perplexing concerned a 1994 Air France flight. While flying over the Paris region, the crew noticed a large brown-red disk hovering on the horizon and constantly changing shape.
The case "has never been explained to this day, and leaves the door open to all possible hypotheses," the agency wrote.
So, do we have neighbors out there, after all?
"I don't have an answer to that," said Patenet. "Even if there is such a planet, given the size of the universe, what is the probability that two civilizations ... will meet or come across each other? I really don't know. It's very complicated. It's incalculable."