The claim: aliens and crashed craft are kept at Area 51
Area 51 is the nickname for the Groom Lake test range in Nevada, about 130 km north-west of Las Vegas. The popular claim is that the United States government keeps recovered extraterrestrial craft and bodies there, usually traced to the 1947 Roswell, New Mexico incident and to Bob Lazar’s 1989 television account of working on alien technology at a site near Groom Lake.
The claim has two parts that deserve different treatment. That the base exists and was kept secret is documented. That it holds alien material is a separate assertion, and the documents available say something else about what the secrecy protected.
What the declassified record says
On 15 August 2013 the National Security Archive published a CIA history of the U-2 and OXCART programs, obtained under the Freedom of Information Act, that named Groom Lake and described how it was chosen in April 1955 as a remote place to test the U-2 reconnaissance aircraft. The first U-2 test flight there took place in August 1955. The history is the first official CIA acknowledgement of the site, and it describes aircraft testing, pilot training and the later A-12 OXCART programme.
Roswell has its own paper trail. In 1995 the General Accounting Office reported on the Air Force records of the 1947 crash and the Air Force explained the debris as a high-altitude balloon train from Project Mogul, a classified programme to detect Soviet nuclear tests with microphones carried aloft. The 1997 Air Force report on the later ‘crash test dummy’ stories connected the reported bodies to parachute tests of the 1950s.
The CIA’s own 1997 account of its UFO role, written by the historian Gerald K. Haines, adds the connection that matters here: reconnaissance aircraft were themselves a source of UFO reports. He says that U-2 and A-12 flights accounted for more than half of the reports made in the late 1950s and 1960s.
Why a high aircraft looks like a glowing light
A U-2 operated above about 21 km, far above airliners at 10 to 12 km. The ground goes dark at sunset, but an aircraft that high is still in sunlight because its own horizon lies far beyond the observer’s. For an altitude h above a sphere of radius R, the Sun can be as far as acos(R ÷ (R + h)) below the observer’s horizon and still light the aircraft.
At 21.3 km that depression is about 4.7°. Near an equinox at Nevada’s latitude, the Sun sinks at about 0.2° per minute, so the aircraft stays lit for roughly twenty-three minutes after the ground is in twilight. Seen against a dark sky, a sunlit aircraft at that height looks like a bright orange or white object with no visible wings, moving at a steady speed and sometimes leaving a lit contrail.
Change the altitude to see why only very high aircraft do this: at 11 km the glow lasts only about two thirds as long as at 21 km. The calculation is geometric and ignores refraction, which adds a little to the time.
How long does a high aircraft stay lit after sunset?
Enter the aircraft’s altitude and your latitude. The result is the Sun depression at which the aircraft leaves sunlight and the minutes after sunset it takes, near an equinox.
How far below the observer’s horizon the Sun can be while still lighting the aircraft.
Near an equinox, ignoring refraction and terrain.
The aircraft altitude used in the calculation.
Working tape
- Radius to the aircraft
6,371.0084 + 21.3 = 6,392.3084 - Horizon cosine, R ÷ (R + h)
6,371.0084 ÷ 6,392.3084 = 0.996668 - Horizon depression
acos(0.996668) = 0.081658 - Sun depression at last illumination
0.081658 × 57.29578 = 4.678636 - Latitude in radians
37.2 × 0.017453 = 0.649262 - cos(latitude)
cos(0.649262) = 0.79653 - Sun’s descent rate at this latitude
0.25 × 0.79653 = 0.199132 - Minutes after sunset
4.678636 ÷ 0.199132 = 23.495091 - Altitude
21.3 + 0 = 21.3
The secret was real; the aliens are not in the record
The documents show a secret base, a secret aircraft programme and a deliberate silence. They also show why that silence created a legend: the aircraft being tested were unlike anything the public had seen, they flew higher than any airliner, and they were reported over and over as unidentified lights. The government let the stories run rather than confirm what was flying.
No declassified document describes recovered extraterrestrial material at Groom Lake. A claim that none exists in documents that are themselves classified is unfalsifiable, so it cannot be tested here. What can be tested is the sighting that starts many of these stories, and for twilight sightings of a steady, high, glowing object the geometry above gives the ordinary explanation.
Why people believe it
Secrecy invited speculation. For decades the Air Force declined to acknowledge the base, and the first public photographs were taken from mountains many kilometres away. Roswell was explained only in 1994, nearly fifty years after the event, and the explanation involved another secret, Project Mogul, which made the original denial look like a cover-up. Reports from pilots, who saw the high aircraft clearly, gave the stories credibility. Each fact is true, and the inference that the secrecy therefore hid aliens is the step the record does not support.
Where to test it
The glow calculation uses the same horizon geometry as the horizon distance tool, and the Sun-depression idea is the one behind the day length calculator. The Roswell balloon story is a question of altitude and line of sight, which the earth curvature calculator also handles.
