A practical checklist of the most-common mundane explanations for purported UAP sightings. Covers Starlink trains, lens flares, conventional aircraft, atmospheric optics, and the small number of sources that account for the majority of false-positive reports.
The Council’s archive is dominated by Inconclusive and Debunked verdicts. This is not because we are skeptical for skepticism’s sake; it is because the most-common explanations for purported UAP sightings turn out, on careful examination, to be mundane. The credibility moat of the Council’s record is built precisely on this honest accounting.
This guide is the checklist serious observers use before concluding that something is anomalous. Run through it. Most sightings will be explained at one of the steps below.
What this guide does NOT do
This guide does not attempt to debunk all UAP sightings. It identifies the most-common false-positive sources, against which any honest observation should be checked. A sighting that survives this checklist is more credible, not because the checklist is comprehensive, but because the most-likely mundane explanations have been actively excluded.
The checklist
Run these in order. Stop when one explains your observation.
1. Starlink train
Since 2019, SpaceX has been launching the Starlink satellite constellation in batches. Newly launched batches travel in close formation — appearing as a precise, evenly-spaced line of bright lights moving silently across the sky. They are visible for typically 1–2 weeks after launch before the satellites disperse to operational positions.
A line of 20–60 evenly-spaced lights moving in a straight line at approximately 95 minutes per orbit, especially within a few days of a known SpaceX launch, is virtually always Starlink. Real-time visibility can be checked at sites like findstarlink.com.
This is by some considerable margin the single most common false-positive UAP source since 2019.
2. Conventional aircraft, especially lit formations
Commercial and military aircraft at altitude can present in unfamiliar ways:
- Approaching head-on, an aircraft’s landing lights can look like a stationary or hovering bright object for extended periods.
- Multiple aircraft in formation (military training flights, ferry operations) can present as a “structured craft” — particularly at night when only the lights are visible.
- Flares dropped by military training aircraft can look like fixed bright lights briefly hovering before descending. This explained Phoenix Lights Event B (Case #00012).
- Ultralight formations flying lit patterns at night accounted for the Hudson Valley wave (Case #00098).
Check flight tracking sites (FlightRadar24, ADS-B Exchange) for traffic in your area at the observation time. Note that military traffic often does not appear on civilian tracking sites.
3. Lens flare
If your “sighting” is something visible only in a photograph or video, lens flare is the first hypothesis to test. See the lens-flare glossary entry for diagnostic features. A bright source somewhere in the frame, an apparent “object” on the line from the source through the optical center of the lens, and the photographer not seeing it at the time, together identify lens flare with very high confidence.
4. Bright planets and stars
Venus is the single most-misidentified celestial object in UAP reports. It can be extraordinarily bright (magnitude –4 or brighter at maximum elongation), often appears low on the horizon where atmospheric distortion makes it appear to “move,” and is unfamiliar to most casual observers.
Jupiter, Sirius, and Mars also account for substantial fractions of false-positives. The 1986 Japan Airlines 1628 case (Case #00094) is partly explained, in some analyses, by misidentification of Jupiter under atmospheric distortion.
Check whether a bright planet is in the direction of your sighting at the observation time. SkySafari, Stellarium, and similar apps make this trivial.
5. Atmospheric optics
Several real atmospheric phenomena look anomalous:
- Hole-punch clouds (fallstreak holes) — circular gaps in altocumulus clouds that can appear suddenly. Possibly contributed to the O’Hare Gate C17 case (Case #00018).
- Sun dogs and parhelia — bright spots in the sky caused by ice crystal refraction. Can look like glowing orbs flanking the sun.
- Lenticular clouds — disc-shaped clouds that form over mountains, often photographed and mis-shared as “UFOs.”
- Mirages and atmospheric refraction — distant objects appearing displaced or distorted, particularly near the horizon.
- Anomalous radar propagation (anaprop) — temperature inversions producing radar returns from ground-level objects that appear airborne. The 1952 Washington flap (Case #00021) was substantially explained by this.
6. High-altitude balloons
Weather balloons, scientific research balloons, and commercial high-altitude balloons (e.g., Project Loon, Aerostar) are released worldwide in substantial numbers. They can:
- Appear stationary at altitude (high-altitude winds are often slow).
- Reflect sunlight at angles that produce bright daytime visibility.
- Travel substantial distances before deflating.
- Produce some of the GoFast-class IR signatures (Case #00034) under specific viewing conditions.
The 2023 Chinese surveillance balloon over the U.S. is the most-public recent example of how a balloon can look genuinely anomalous to observers without context.
7. Drones and small UAS
Recreational and commercial drones are now ubiquitous. They can:
- Hover silently for extended periods.
- Produce unusual lighting configurations.
- Move in patterns inconsistent with conventional aircraft.
- Appear at low altitude in restricted airspace (a frequent FAA enforcement issue).
A “hovering object with multicolored lights” within line-of-sight of a populated area is, with high prior probability, a consumer drone.
8. Satellite reflections, ISS, Iridium flares (residual)
Beyond Starlink, individual satellites can produce brief bright reflections. The ISS is often mistaken for a UAP. Iridium flares, while reduced since the original constellation was largely de-orbited, still occur from the next-generation Iridium satellites and other reflective spacecraft.
9. Camera artifacts other than lens flare
- Pixel noise in long-exposure photographs producing apparent moving “objects.”
- Sensor hot pixels appearing as fixed bright points.
- Motion blur of stars or aircraft producing apparent “rod” shapes.
- CMOS rolling-shutter artifacts distorting fast-moving objects (e.g., propeller blades or rotor blades looking impossibly bent).
10. Real but classified aviation activity
Some sightings turn out to be real aircraft that were not publicly disclosed at the time. The Roswell incident (Case #00003) is the clearest historical example: real classified activity (Project Mogul) producing a real anomalous-looking event with a mundane explanation that took 47 years to be made public.
This category is the hardest to rule out and accounts for some of the most legitimately puzzling cases in the historical record.
When the checklist doesn’t explain it
If you have honestly worked through this checklist and your observation is not explained, document it carefully (see Field Guide FG-001) and submit it to the Council. The honest answer for many such cases is “unexplained-by-checklist but not necessarily extraterrestrial” — that is, in our terminology, Inconclusive. That is a respectable verdict and often the correct one.
Council recommended
This guide does not require gear. It requires discipline and the willingness to honestly try the mundane explanations first.
For supporting tools when working through this checklist, the Council recommends:
- A flight-tracking app (FlightRadar24 or similar)
- A planetarium app (SkySafari, Stellarium)
- The findstarlink.com or Heavens Above visibility tools
- A weather radar reference for the observation time and location
Related cases
- Case #00012 — Phoenix Lights Event B — the textbook case of a famous sighting with a documented mundane explanation (military flares)
- Case #00098 — Hudson Valley wave — the textbook case of a multi-year wave with a documented mundane explanation (ultralight formations)
- Case #00021 — Washington D.C. flap 1952 — the textbook case of radar contacts explained by atmospheric phenomenon (temperature inversion)
- Case #00003 — Roswell — the textbook case of a real classified-program explanation taking decades to become public (Project Mogul)