Satellite image of the Groom Lake military installation.
Area 51 is a secret military installation (37° 14.6' N, 115° 47.61' W, elevation 4,383 feet) on the edge of Groom Lake, Nevada.
Existence of the base is not publicly acknowledged for security reasons and civilian maps of the region carry no mention of it, only a travel restriction warning. Eyewitness reports from individuals living near the compound testify to unusual aerial activity, including strange craft flying over the mountains and unexplained lights in the night sky. Such sightings are hardly surprising considering that the US Air Force has for many years test flown some of its most covert vehicles there, including the U-2 spy plane, the B-2 Stealth bomber, and the SR-71 Blackbird. When objects as commonplace as Venus or lozenge-shaped clouds can be taken for unidentified flying objects, it should raise few eyebrows that new aircraft with strange appearance, unfamiliar lighting, and extraordinary performance capabilities might be similarly misinterpreted. Some of the latest piloted military hardware can fly at speeds and in ways comparable to those claimed, in early flying saucer books and films, for alien spacecraft in Earth's atmosphere. There are now something like genuine, intelligently-directed UFOs on this planet – and they are human-built. Yet despite the obvious possibilities for misidentification of secret planes with flying saucers, there are those who insist that the Air Force is doing more in the wilderness of the Nevada desert than test-flying the latest high-performance jets.
The claim from some ufologists is that Area 51 also serves as a facility for examining captured extraterrestrial craft and alien corpses. This view was popularized in the film Independence Day, the producers of which were requested by the government to take out all references to Area 51. When they refused, the government withdrew its offer to assist with the movie. Such secrecy naturally serves to stoke the fires of speculation. There are obvious reasons for the Department of Defense to keep the Nevada installation out of the public eye if some of the most advanced military hardware in the world is being put through its paces there. On the other hand, the heavy blanket of security enveloping the base allows those who want to put forward more extreme views can do so, safe in the knowledge that it is just about impossible for them to be proved wrong.