UFO is short for unidentified flying object. For the first there are people reporting this queer object, it has been connected with outer space aliens. Many people believe its space shuttle of aliens which are looking chances to launch an invasion of our planet. Maybe it sounds a little like that of Sci-Fi movies of Hollywood director Steven Spielberg, but the phenomenon of UFO indeed intrigued serious concerns of western countries like America and Britain.

Let's see how witnesses say about it. A witness from welsh says he see aliens kidnapping a dog. He is quoted as saying that he saw several "huge space shuttle" while camping outside with his friend. And one of these "huge space shuttle" took away his dog, car and tent. He believes these are UFO. Actually, according to British media, since the establishment of UFO program in 1950 by British defense department, it has received more than ten thousand reports on UFO phenomenon, most of which is hard to be identified scientifically.

What's more sensational about UFO comes from unclassified British documents. According to the unclassified documents, dubbed as "X-document", a bomber of British royal air force was once being traced by a UFO when flying across the Atlantic in 1977. Journalist with "Observer", a British newspaper, who has seen the relevant documents, is quoted as saying that back then, the bomber was flying through the Biscay bay at a height of 43 thousand feet. And all of a sudden, "an object" edged near from a distance of 6.5 kilometers away without any warning and emitted strong light like that of aircraft landing light. The object followed closed in the route of the bomber. And suddenly the strong light was replaced by orange white-hot light while glistening green light spots shined at the lower right corner of it. And then the crewmen saw the object flied away in an angle of forty five degree with shocking speed. Obvious the crewmen can't make a reasonable explanation of it, nor the following investigation borne any fruit.

But most legendary episode about UFO is the Roswell incident in US. In Fifth, July, 1947, Mac Brazel, owner of a farm 120 kilometers southwest to Roswell heard a thundering explosion. The next day, he found many special metal fragments in a range of four hundred meters around his farm. And then he reported this to military department. And the colonel found a metal disk-shaped ruin when checking the site and brought it back to military base. Besides, Grady, a civil engineer also found metal disk-shaped ruin. Several corpses were scattered around it. These corpses were extremely thin and only with a height of 100 to 130 centimeters and a weight of 18 kilograms. They had big heads, big eyes, small mouths and no hairs. But American government made a secret of it.

In all, countless reports about UFO are heard, but most of them ended up being not explained. And some also argue that these are but lies made by people who want to make a name through UFO. But there are also people believe in the existence of it. Through now people's opinions over it vary, the development of science and technology will eventually unlock the mystery, so let's wait and see.