The mother of all flying-saucer stories

One of the main building blocks for the conspiracy theories favoured by Xphiles is the belief that alien spacecraft crash-landed in Roswell, New Mexico, 51 years ago - and that the US government has been hiding the truth at a top-secret installation called "Area 51".

Eyewitnesses are sure that something really happened in 1947, just outside the small American town of Roswell. They say a flying saucer crashed in the desert, apparently scattering ET body bits and other unidentifiable stuff over the fringes of local farm lands. Almost immediately a press statement was issued: "The Roswell Army Air Field has gained possession of a flying disc on a ranch in the Roswell region." This is generally regarded as the first official reference to flying discs.

The very next day, the army had a whole new version of events: the "flying disc" was a case of mistaken identity. All that had crashed was a weather balloon, officials claimed.

But the story didn't stop there. Over the decades new evidence would appear; slowly but surely the "truth" began to seep out. It now appears there was indeed a cover-up - but one related to secret US military operations.

In the late 1940s the Roswell Army Air Base was home to the air-force squadron which had dropped atomic bombs on Hiroshima and Nagasaki in 1945. In 1947, with the Cold War just starting, the US suspected the Soviet Union was developing its own atomic bomb; the US military wanted to know what the Soviets were doing. Project Mogul apparently involved special weather balloons with equipment that might record Soviet atomic tests from far away - hence the secrecy. As for Area 51 in Nevada, the UFO-spotters who flock to the desert hoping to see alien crafts over the barbed wire are probably watching top-secret US bombers being tried out in test flights.

Still, some say this is yet another cover-up. The aliens have landed, and that's that. One way or another, in the interest of objective reporting, the press is obliged to publish the "truth" as it is officially issued on any given day. So, should you believe what you read in the papers?