As a MUFON investigator, you will run into many more UFO sightings that turn out to be conventional objects of natural or human-made origin than you will UFOs that turn out to be genuine UFOs, which may have "high strangeness" aspects to them. When you have an identification to beyond a reasonable doubt that the stimulus of the sighting report was one of these conventional objects (or phenomena), then you designate the UFO sighting stimulus as an IFO (Identified Flying Object). Of course, the IFO may not be an object and it may not be flying, but this is the usual designation of identified stimuli. For example, you may feel convinced that what someone saw was actually the spotlight at the nearby used car lot shining on the underside of a cloud. Nothing is flying here and the light spot on the undersurface of the cloud is not an "object." You get the idea.

Check out this general presentation about IFOs (long download) that Keith Rowell, Assistant State Director, gave to the March 14, 2006, meeting of Oregon MUFON.

Common (and Not So Common) IFOs

To help you and the interested public identify the common objects or phenomena mistaken for genuine UFOs, we have assembled a table with the usual characteristics of these objects or phenomena.

Note that people who report what are actually IFOs as UFOs many times see them under somewhat unusual circumstances, so their misidentification is perfectly understandable. Also, many people are not very knowledgeable about how stars, planets, aircraft, etc., normally behave because of their lack of study. The vast majority of UFO sighters are just trying to honestly describe something puzzling they have seen. It also seems to be true that once people get the idea they might be seeing a flying saucer, then their imaginations and the excitement of the moment can cause them to over-interpret the object they are seeing. It is the investigator's job to sort all of this out.

The information about Nocturnal Light IFOs in the following table was taken mostly from Allan Hendry's excellent UFO Investigator's handbook: The UFO Handbook: A Guide to Investigating, Evaluating, and Reporting UFO Sightings (Doubleday, 1979). These are UFOs reported at night that became IFOs upon competent investigation by a knowledgeable UFO investigator: Allan Hendry. He did his study of over 1300 UFO reports in the late 1970s. 


Common IFOs 

IFO Stimulus



Stars appear at dusk, dawn, and night. They can be any rainbow color and twinkling; white, blue, red are most common. They move across the sky in an arc around the north polar star (Polaris). They move slowly, 15 degrees of arc an hour (about a fist and a half at arm's length). Some stars are prominent: Sirius, Vega, Capella, Arcturus, and a few others. Note that stars can appear to make small movements (due to autokinesis — small involuntary eye movement when staring at an object). They've also been described to make back and forth or up and down movements, which, of course, they do not do. According to Hendry, stars and planets make up about a third of Nocturnal Light IFOs.


Venus is the champion of the easily visible planets: Venus, Mars, Jupiter, and Saturn. These planets follow the ecliptic (the path of the sun through the sky) and rise in the east and set in the west. They move slowly but not exactly like the stars; planets even "double back" sometimes (retrograde motion for small distances). Venus can be 100 times as bright (whitish) as prominent stars and is quite easily seen in the morning and evening at times. It can even be seen in the daytime at its brightest in some years. Mars can get quite prominent and bright (red) in certain years. In high-powered binoculars, these planets are seen as small disks unlike stars. According to Hendry, stars and planets make up about a third of Night Light IFOs.

Advertising Airplanes

In the 1970s, these low-flying (around 1000 feet) light planes with advertising slogans flashing underneath their wings naturally fooled many people. They flew at low level over highly populated areas. You could not see the body of the plane. Many people added details that weren't there such as that the lights rotated, it hovered, etc. Your assistant director saw one over Portland in the 1970s and it did indeed look quite a bit different from the usual things in the night sky. According to Hendry, ad airplanes accounted for almost a quarter of Night Light IFOs in his study.


Aircraft are many and varied. They can be seen night and day. Running lights at night on many aircraft are red and green wing tip lights with a white or red light on the tail. (Bigger aircraft like airliners may not have the red and green wing tip lights.) Usually one or more periodic (one second) flashing light(s) are present on larger airplanes. Whitish landing lights are switched on near runways. These can be very bright, looking head on at them. Unfortunately, for identification purposes, the variety of lights on aircraft is large. Military aircraft can have very unusual lights in unusual places.

Aircraft can be covered by your thumb at the end of your outstretched arm, even if they fly very low over you. You must be close to an airport for flying aircraft to be very large (bigger than your thumb at arm's length). Most aircraft are not visible in the sky for over a couple of minutes at most because they are traveling from here to there and you usually see them along their flight path. But sometimes aircraft do circle or otherwise pass through your view of the sky such as crop duster aircraft do.

Aircraft can be strange-looking to the average person sometimes. Secret, experimental government aircraft are virtually never flown low over populated areas. You might see (or hear) a very high flying (above 35,000 feet) secret craft if you live under their flight path. For example, the Los Angeles area between Area 51 and/or Palmdale/Lancaster/Edwards AFB and their Pacific Ocean MOA. It is very rare for high flying craft to zig zag or otherwise make erratic movements except for possible fighter jet simulated battles over Area 51, for example. According to Hendry, aircraft were about 20% of the total of Night Light UFOs.

Blimps are non-rigid, football-shaped, helium-filled aircraft. They cruise around 70 m.p.h. (very slow for an aircraft) and are around 150 or so feet long. The commercial ones are used for advertising. The Goodyear blimp(s) is the most famous. They can be seen in the day or at night. Their movements can be very unusual since they are usually trying to be seen over a populated area for advertising. Military blimps are rarely seen in the U.S. except for the tethered variety. These are tied to the ground and stationary, can be up to 15,000 feet above sea level. They are seen near the Mexico border.

Helicopters are usually loud and unmistakable because of this within a couple of thousand feet of you.  Their running lights are generally white and red and may be located on the tail and bottom.  Their movements can be in any direction and change fairly quickly and include times of hovering in place. Police surveillance helicopters are seen over urban areas. These are usually small to medium in size and can be white or dark. Military and industry helicopters of large and small varieties are occasionally seen over rural areas. Military and police may operate at night, but most helicopter activity is in the daytime. Occasionally, Coast Guard rescue helicopters are seen flying up and down the seacoast.

Meteors/Space Debris Reentries

Meteors can streak through our sky in daytime or night time. They can be just a bright streak of green, orange, or white, or they can be much closer (rarely) with obvious rumbling, hissing, or other noise with a cloudy, smoky trail. You might even smell them if they are extremely close! Most meteors are very small little streaks in the night time usually originating at a "radiant" point within certain constellations such as the Perseids and Leonids meteor showers. Space debris is somewhat similar, but a particularly prominent piece of space debris coming back to Earth will be known and announced by NASA or other government agency sometimes. These phenomena don't last over two minutes (reentries) or 10 seconds (meteors). A small percentage of the total.


Satellites appear usually like fast moving stars. Sometimes they can be fairly bright, however. They can appear in any part of the night sky and move continuously and disappear suddenly. (They may go in and out of the Earth's shadow as they orbit the Earth.) They don't have large erratic movements, however; their motion is smooth and continuous. They may appear to brighten and dim as they move along as they turn different sides to the sun illuminating them. A small percentage of the total.


The moon is usually quite recognizable except sometimes when it is pretty full on the horizon. Then it looks quite big and may be orangish and look like a "craft" behind some nearby trees or buildings. The moon is actually about one half a degree of the full 360 if you turn around in a circle pointing at the horizon. It looks quite big in the sky and in fact will, many times, be bigger than passing airplanes unless the airplanes are quite close to you. Surprisingly, you can cover the full moon with your thumb tip held at arm's length. A small percentage of the total.

Prank Balloons

Prank balloons may be launched occasionally by teenage boys (or mentally teenaged men!) to have some fun. Look for this around July 4th, Halloween, New Years Eve, etc. These are balloons and travel on the wind, but may go up and down with the wind currents. The main motion is usually upward, however. These can get their buoyancy from helium or hot air. They may have small lights attached. This was more frequent in the era of the 1950s, 60s, and 70s when newspapers and TV stations would report UFO sightings much more than they do today. Not common.

Search Lights

Search lights can be seen if they strike clouds or other objects in the sky. Their beam may also be seen as a column of lighter toned air if the air is very dusty or foggy. They can be any color. Search lights are usually associated with advertising such as at a car dealership. Not common.

Other Balloons

Other balloons are weather balloons, hot air balloons, tethered surveillance balloons (at the U.S. border), and various experimental balloons, etc. Weather balloons are launched daily at many meteorological installations around the U.S. They are six or so feet in diameter and opaque and carry a small instrument package aloft. They rise quickly in a few minutes and are then hard to see with the naked eye. They ride on the air currents to thousands of feet. 

Hot air balloons are readily seen and identified by most people on still days when they are generally launched. They are large in the sky at 50 to 100 or more feet in size and have a gondola at the bottom. They travel slowly and at low altitudes of 500 to 1000 feet or so. You can wave to the "martians" in the gondola if you are very near one of these, and they will wave back. 

The tethered surveillance balloons are in the states bordering Mexico and look like blimps with an oblong shape with protuberances. They stay in one place, but if you are driving along the freeway, they might seem unusual till you see them clearly. 

Various science and technology oriented installations may release balloons of various descriptions on occasion, but unless you are very close to one of these installations you will only see these types of balloons as possibly a high altitude speck in the sky comparable in size to Venus at the most. It would be a truly anomalous object that might be hard to identify and track down, though most operations launching these balloons are not part of secret government projects. Thus, you might get a positive ID. Not common.

Missile Launches

Missile launches in the U.S. are essentially nowadays from the east or west coasts going out over the Atlantic or Pacific. You will only see one if you are close to Vandenberg AFB, Calif. or Patrick AFB, Fla. Missiles generally leave a trail of smoke and steam in the sky at the top of which is the missile, which may be hard to see without binoculars. Not common.

Fixed Ground Lights

Fixed ground lights are found in a wide variety of shapes, sizes, and colors. Unusual circumstances might lead to misidentification at times. Knowledge of longterm human activity in the area of observation is necessary to identify fixed ground lights. Not common.


These are used mostly by the military to light up the night sky or ground, and they drift slowly to the ground over some minutes time. If you view them with binoculars, you will probably be able to observe the smoke they give off. Multiple flares would fall independently of each other. A distress flare would be fired from the ground into the air and would not rise above 500 to 1000 feet. Military flares would be dropped from an aircraft probably. Not common.


Sometimes birds can be briefly mistaken for a true unknown, but the circumstances of observation would have to be quite unusual to fool people: for example, in short duration or difficult viewing circumstances like fog. Herons and cranes are the largest common birds. Flocks of birds at night illuminated from below might be confusing. Not common.


Kites of today come in quite a variety of shapes, sizes, and colors. Their flight behavior would be a back and forth flight path or a stationary one. Kite enthusiasts congregate at beaches or parks sometimes. Not common.


Unusually shaped clouds might fool a few people. The common lenticular cloud appears as a stationary object near mountain tops in some regions. Not common.

Test Clouds

Very rarely, scientific, technical, or military activities result in test clouds, which can be various colors, but usually do not have definite shape, at least for very long. Tracking down the source might be difficult. Rare.


The common hot weather mirage is mostly a desert Southwest phenomenon. Optical effects due to differently refracting layers of air can make it appear that solid objects are being observed when they are actually just the result of reflection and refraction. Not commonly reported.


The moondog is an effect analogous to the sundog, which appears on either side of the sun or moon when a thin layer of ice crystals are between the sun or moon and the observer. Rarely reported.

Window Reflections

Window reflections are understood by most all observers since they are so common. When a person removes his or her glasses or goes outside to see if the observed effect is still there, he or she is unconsciously acknowledging that they know about reflections and their power to mislead us sometimes. Very rare.