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What UFOs Are and Are Not

Don Berliner, 2002

original source |  fair use notice


For more than 50 years, men and women around the world have reported sights in the sky that are strange to their experience and understanding. Inasmuch as many of these sights appeared to be solid objects having impressive performance, they have become known as Unidentified Flying Objects (UFOs) or, colloquially, flying saucers. Their positive identification is one of the major public/scientific challenges of the era, with a significant number of these sights so far defying all reasonable efforts at classification. We take a look at the most common explanations for these sights.

Explained Sightings

It is generally agreed that most sights initially called UFOs are quickly revealed by qualified analysts to be common phenomena that have been misidentified by inexperienced or impatient witnesses. Estimates of explained UFOs run in the 80% - 90% range. With the total number of observations well into six figures, unexplained UFOs can thus be counted in the thousands or perhaps tens of thousands.

Atmospheric Phenomena

As most UFOs are said to have been seen within a few miles' range, the majority seem to be within the Earth's atmosphere. They can therefore be divided into two major categories: natural phenomena and artificial phenomena.

Natural Phenomena

The following types of natural atmospheric phenomena range from extremely common to rare, but all have played roles in confusing innocent observers into thinking they were seeing UFOs.

1. Clouds

While the great majority of clouds are obviously evolving, shapeless blobs, one type--lenticular--strikingly resembles disc-shaped UFOs. Such clouds are most commonly seen in mountainous country but can also form on the downwind side of large hills. They can appear to have sharp edges and are frequently symmetrical. But by studying them carefully and watching their movement, their true nature should become apparent.

2. Birds

Individual birds do not look like UFOs, of course. But flocks of them seen under unusual conditions--such as in hot weather when the heat waves above a large, paved surface distort their appearance--can look unusual because of their changing shape and swooping motions. Careful, patient observation will almost always reveal their true nature.

3. Meteors

Meteors probably trigger more UFO reports than any other phenomenon. They move far faster than anything else in the night sky and can exhibit a variety of colors. The largest of them--called fireballs--can be seen simultaneously over hundreds of miles and appear to move much more slowly than ordinary meteors. But they all eventually burn out. And none appears to change direction or speed.

4. Mirages

This is a commonly used explanation for UFOs but is rarely applied correctly. Mirages cannot be seen more than 1° above or below the observer's horizon. Anything seen high in the sky cannot be a mirage, no matter who says it can be.

Artificial Phenomena

Since the first man-carrying balloon lifted off in 1783, the sky has become increasingly crowded with manmade objects, although the crowding is rarely apparent more than a few miles away from a major airport. Unusual viewing conditions such as rapidly moving, scattered, or broken clouds can briefly make something very common look very unusual.

1. Airplanes

Most airplanes are shaped like conventional airplanes, with a tail in back and wings toward the front. But some are not, such as delta (triangular) winged fighters and supersonic transports. Some have their wings in back and their horizontal tails in front, while others have two parallel fuselages. But almost all of them climb, descend, and turn like airplanes, except for VTOL (Vertical Take-Off and Landing) airplanes, such as the Harrier and the new Lockheed-Martin F-35, which is not yet in production. None flies the way UFOs are said to fly, with violent maneuvers, silent hovering, silent high-speed flight, and spectacular acceleration. Claims that super-secret airplanes resemble UFOs lack even the slightest factual support.

2. Balloons

All balloons float with the wind and cannot possibly out-speed any type of airplane. They are also unable to change speed or make turns, except very gradually, as the wind changes. Toy balloons are the least controllable of all and just bob along until they pop or leak enough gas to come down. Human-carrying balloons, the most common type of which uses a propane burner to heat the air in the bag, are silent except during the burner's intermittent operation. Such balloons are usually teardrop shaped, although more and more have novel shapes (for example, soft drink bottles, ice cream cones), which make them even more recognizable as balloons.

3. Missiles

Missiles can look like cylindrical UFOs, but they are launched only from well-known sites and are never directed over populated areas. The most common launch sites are Wallops Island, VA; Vandenburg AFB, CA; and Cape Kennedy, FL. Almost all launches of large missiles or space launchers are known in advance and publicized. With rare exceptions, such flights begin straight up and finish straight down. Level flight is rare, except for small missiles in combat situations and training.

4. Satellite Reentry

The reentry into the atmosphere of a satellite or its launcher can be highly spectacular, resembling a large meteor, although more colors may be visible at one time due to the variety of types of material in a satellite. Reentries of large, manmade objects are well publicized in advance.

5. Other

Searchlights, singly or in groups, are sometimes used to attract attention to the opening of a business, such as a gas station or used car lot. When they sweep around and reflect off low clouds, they can look like oval lights flying fast in tight circles.

Some airplanes fly at night with batteries of blinking or moving lights used for advertising purposes, and the same can be said of blimps. They can give the impression of quite strange craft unless the observer is patient.

Exoatmospheric Phenomena

Natural Phenomena

1. Stars

Nothing in the night sky is more common, well known, and identifiable than stars. But an especially turbulent atmosphere can make a star--especially one near the horizon--appear to jump or bounce around, or to twinkle or change colors. However, all stars move so slowly across the sky that you have to line one up with something stationary to detect any movement, which is always in a straight line.

2. Planets

Planets generally look like bright stars and move in a similar fashion. But at certain times and in very clear weather, planets like Venus can look entirely too bright to be planets. Careful observation will reveal their planetlike motion.

3. The Moon

The only natural sight in the sky that has apparent size and shape is our moon, which can be seen at any time of the day or night, unlike stars and planets, which are almost never seen in the daytime. The shape of the moon varies from a thin crescent to a full circle but it is still the moon. It rises in the east and sets in the west. It does not move quickly or change direction. When seen through fast-moving, broken clouds, the moon can appear to move.

4. Comets

One of the more rare and mysterious sky sights, comets can occasionally be seen with the naked eye. A comet looks like a smear of light that hangs in the sky, night after night. A comet does not appear to move.

Artificial Phenomena

1. Satellites

Manmade satellites move in a straight line, at a steady speed. They do not change speed, nor do they change direction. Every satellite, from the smallest to the largest, looks like no more than a point of light without any shape.

Indeterminate Explanation

Many UFO sighting reports are first placed in the indeterminate category until more information can be acquired. Most are then placed in one of the categories of known phenomena, or are listed as unexplained. Some remain indeterminate.

1. Insufficient Information

Many reports can never be explained due to the lack of important information. Without a precise date and time, it is almost impossible to check them against air traffic records or satellite launches. Without the name and background of the witness(es), there is no way to determine if the information is reliable.

2. Unreliable Source

If it is determined that the information in a UFO sighting report came from one or more persons whose word cannot be trusted, the case will remain indeterminate and thus worthless.

Unexplainable Reports

Some UFO reports contain enough information from good sources that they should be explainable, but the information does not describe anything familiar. In this case, the report is considered a genuine UFO, which means it appears to have been an object that was seen flying but that remains unidentified. This is the heart of the UFO mystery, and the object of considerable effort aimed at explaining what has puzzled so many people for so many years in all parts of the world.


Genuine UFOs usually have particular visual characteristics. Most of them have simple geometric shapes (discs, ovals, spheres, cylinders) that are unlike airplanes, along with sharp edges and metallic-looking surfaces that suggest a manufactured origin.


Otherwise unexplained UFOs fly in very unusual ways that are not characteristic of airplanes. They can exhibit spectacular acceleration, silence while flying fast or hovering, and violent maneuverability.

Non-Earthly Craft

When all possible conventional explanations have been discounted, it can be a great temptation to conclude that a particular unexplained UFO must be an extraterrestrial (ET) vehicle. Using the process of elimination, however, is valid only when all possible alternative explanations have been considered. In the case of UFOs, there is no way to know all possible explanations.

The closest one can get to justifying the ET answer occurs in the case of a UFO that is not merely beyond all known answers but also displays a very unusual appearance and/or very unusual behavior. Lacking this, a report must be considered simply "unknown."

In order to prove conclusively that a UFO is alien, one must have direct proof, not merely an absence of other answers. This proof would probably have to be physical evidence, such as a piece of metal that two or more scientific laboratories agreed could not have been made on Earth.

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