Scientific Explanations for UAP Sightings -

Most UAP sightings turn out to have scientific explanations. Here are the categories of conventional phenomena that account for the vast majority of reports.

The All-domain Anomaly Resolution Office has received over 1,600 UAP reports since 2021. According to AARO Director Jon Kosloski, the office has resolved hundreds of cases to commonplace objects such as balloons, birds, drones, satellites, and aircraft. In closed cases from 2023 to 2024, approximately 70 percent were identified as balloons, 16 percent as drones, 8 percent as birds, 4 percent as satellites, and 2 percent as conventional aircraft. These numbers align with a pattern that stretches back to the earliest government investigations: the overwhelming majority of unidentified aerial phenomena have scientific explanations.

This National Geographic documentary examines how scientists use AI, radar systems, and physics to analyze UAP reports. The episode demonstrates how optical effects and sensor limitations can make ordinary objects appear extraordinary.

TL;DR

The U.S. government and independent researchers have identified several categories of conventional phenomena that explain the vast majority of UAP reports. Balloons, drones, planets, satellites, birds, and atmospheric effects like sprites account for 94 percent or more of cases investigated by official programs. The remaining cases that resist explanation typically lack sufficient data to reach a definitive conclusion, rather than exhibiting characteristics that defy known physics. This does not mean every sighting is trivial or insignificant , some cases involve complex interactions of multiple phenomena that are genuinely difficult to untangle. Sources linked below.

Timeline

1948: Project Sign, the first official U.S. Air Force UFO investigation, publishes its “Estimate of the Situation,” concluding that some sightings might have extraterrestrial explanations. Air Force Chief of Staff General Hoyt Vandenberg reportedly rejects the conclusion and orders the document destroyed.

1953: The Robertson Panel, convened by the CIA, reviews 2,300 UFO reports and concludes that virtually all could be attributed to misidentified conventional objects. The panel recommends a public education campaign to reduce public interest in UFOs.

1968: The University of Colorado publishes the Condon Report, a 965-page scientific study of UFOs. Director Edward Condon concludes that “further extensive study of UFOs probably cannot be justified in the expectation that science will be advanced thereby.” Approximately 95 percent of cases examined had conventional explanations, though critics noted about one-third remained unexplained in the raw case data.

June 2021: ODNI publishes its Preliminary Assessment on UAP, reporting 144 cases from military sources. Of these, only one was resolved with high confidence (a deflating balloon). The report states that UAP “probably lack a single explanation.”

January 2023: ODNI’s first consolidated annual report covers 510 UAP cases. AARO reports that many resolved cases involved balloons, UAS (drones), or clutter such as plastic bags.

March 2024: AARO releases Volume 1 of its Historical Record Report, a 63-page review spanning 1945 to 2023. The report concludes that “AARO has not found any verifiable evidence of extraterrestrial technology” and attributes most historical cases to misidentified conventional objects.

November 2024: AARO publishes its FY2024 consolidated annual report covering 757 new cases. The report specifies that among closed cases, approximately 70 percent were balloons, 16 percent were drones, 8 percent were birds, 4 percent were satellites, and 2 percent were aircraft.

Scientific Explanations: Balloons and Drones

Balloons are the single most common explanation for UAP reports received by AARO. According to the FY2024 consolidated annual report, approximately 70 percent of resolved cases were attributed to balloons of various types, including weather balloons, research balloons, and high-altitude platforms. Drones, or unmanned aerial systems, accounted for 16 percent of resolved cases.

The prevalence of balloon explanations has historical precedent. In 1947, the Roswell debris was initially reported as a “flying disc” before the Air Force identified it as a weather balloon (later confirmed to be a Project Mogul balloon designed to detect Soviet nuclear tests). In 2023, the U.S. military shot down four objects over North American airspace in a span of eight days: a confirmed Chinese surveillance balloon off the coast of South Carolina, plus three smaller objects over Alaska, the Yukon, and Lake Huron. NORAD Commander General Gregory Guillot later testified that the three smaller objects were likely “benign” balloons, though they were never recovered.

Drones present a different challenge. Small consumer and commercial drones can appear on radar and infrared sensors as unidentified objects. In late 2023 and early 2024, a series of drone flights over Langley Air Force Base in Virginia prompted a base-wide alert and relocation of F-22 fighter jets. NORAD Commander Guillot told the Senate Armed Services Committee in March 2024 that the volume of drone incursions was unexpected, but confirmed the objects were drones, not anomalous phenomena.

Planets and Stars

The planet Venus is responsible for a disproportionate number of UFO reports. Astronomer Jonathan McDowell estimates that before dashcams and smartphones began capturing space debris reentries, Venus caused approximately half of all UFO reports. Venus appears as an extremely bright light near the horizon at dawn or dusk, and its apparent motion against passing clouds can create the illusion that it is moving. Jupiter, at its brightest, can also be mistaken for an aircraft or hovering object.

This pattern has been documented since at least the 1950s. The U.K. Ministry of Defence, which operated a UFO reporting desk from 1950 to 2009, frequently identified Venus and Jupiter as the source of civilian UFO reports. The ministry’s files, released to the National Archives in 2008, include dozens of cases where bright planets were confirmed as the reported object.

Bright stars such as Sirius and Arcturus, and planets like Mars at opposition, can also trigger reports. When thin high-altitude clouds pass in front of a stationary bright object, the resulting apparent motion can fool the observer into believing the object is traveling across the sky.

Atmospheric Phenomena

Several atmospheric phenomena produce light displays that can be mistaken for unidentified objects. Sprites, ELVES, and jets are transient luminous events (TLEs) that occur above thunderstorms, at altitudes of 35 to 80 miles. They produce brief flashes of red, blue, or green light lasting milliseconds to seconds. These were not photographed until 1989, when University of Minnesota researchers captured a sprite on video. Before that date, reports of luminous objects above thunderstorms were routinely dismissed.

Tel Aviv University geophysicist Colin Price published research in 2009 demonstrating that sprites could explain some UFO sighting reports. Price’s work showed that lightning from thunderstorms excites the electric field above, producing a flash of light visible from the ground. These events can appear as colored lights moving rapidly at high altitude.

Ball lightning, a rare and poorly understood phenomenon, may also account for some sightings. Physicist Colin Keay proposed in 2010 that meteors entering the atmosphere could trigger electrical connections between the upper atmosphere and the surface, producing ball lightning events visible from the ground. The BBC reported on Keay’s theory, noting that the 1978 Valentich disappearance in Australia could potentially be explained by a meteor-triggered ball lightning event.

Lenticular clouds, which form in lens-shaped layers near mountains, can also appear as hovering disc-shaped objects, particularly when illuminated by the sun at low angles. Temperature inversions can produce mirages and false radar returns that mimic the behavior of physical objects at altitude.

Optical Illusions and Camera Artifacts in UAP Sightings

FLIR (forward-looking infrared) cameras, the type used in the famous Pentagon UAP videos, produce imagery that can mislead even trained observers. The camera’s rotating gimbal mount creates a visual artifact that makes distant heat sources appear to rotate independently. The GIMBAL video, recorded in January 2015 by a Navy F/A-18 pilot off the U.S. East Coast, shows a rotating object that analyst Mick West demonstrated could be explained by the camera’s gimbal rotation combined with the jet’s forward motion.

The GOFAST video, also from 2015, shows a small object apparently skimming the ocean surface at high speed. West’s analysis demonstrated that the object’s apparent speed was an illusion caused by parallax: the Navy jet was traveling at several hundred knots, and the object was likely a slow-moving balloon or bird at medium altitude, appearing to move fast against the stationary ocean background. AARO’s own analysis of the GOFAST video, presented in 2024, calculated the object at approximately 13,000 feet with a ground speed of 45 miles per hour, consistent with a drifting object at wind level.

FLIR cameras also produce “white-hot” and “black-hot” images that can make distant objects appear to glow, vanish, or change shape. When a camera switches between these modes or adjusts its zoom level, an object’s apparent size and brightness can change dramatically, creating the illusion of impossible acceleration or deceleration. This type of analysis is at the heart of UAP debunked by independent researchers, who focus on ruling out conventional explanations before considering anomalous ones.

Critics, including the VFX artists at Corridor Crew, have demonstrated how camera artifacts, compression, and lens effects can make conventional objects appear anomalous on video. Their analyses of Pentagon UAP videos show how focus transitions, pixelation, and parallax combine to create the appearance of extraordinary performance by ordinary objects.

Birds, Insects, and Clutter

According to AARO’s FY2024 report, 8 percent of resolved UAP cases were attributed to birds. Large birds such as pelicans, geese, and vultures can appear as unidentified objects on radar, particularly when flying in formation or at unusual altitudes. Infrared cameras can detect the body heat of birds, producing bright spots in thermal imagery that appear as fast-moving objects.

Insects, particularly large swarms, can produce radar returns and appear as moving objects on FLIR cameras. The ODNI 2023 report specifically noted that AARO had resolved cases to “plastic bags and other airborne clutter.”

Bats, which are active at dawn and dusk (the same hours when UFO reports peak), can produce radar returns similar to small drones. In areas near military bases where radar sensitivity is heightened, even small biological objects can appear as unidentified contacts.

Satellites and Space Debris

Satellites are a common source of UFO reports. The International Space Station, visible to the naked eye, produces a bright moving light that crosses the sky in approximately four minutes. Starlink satellite trains, launched by SpaceX since 2019, produce a string of bright dots that has generated thousands of UFO reports worldwide.

Space debris reentries produce dramatic fireball displays that can appear as structured objects moving at extraordinary speed. In February 2023, a meteor that entered the atmosphere over southern England produced reports of a “fireball” with structured edges. Analysis showed it was a small asteroid fragment burning up during atmospheric entry.

The 2024 AARO annual report notes that 4 percent of resolved cases were satellites, and that AARO reached preliminary assessments on Middle East cases as possible satellite flares , brief bright reflections from solar panels on orbiting satellites.

Military and Foreign Technology

Some UAP reports turn out to involve foreign military technology. The Chinese surveillance balloon shot down off South Carolina in February 2023 was tracked by NORAD for days before being publicly identified. The 2023 Langley AFB drone incursion involved what officials described as small, sophisticated drones of unknown origin.

Jeff Wise, writing for New York Magazine’s Digital Intelligencer, has suggested that some military UAP reports could reflect electronic warfare effects rather than physical craft. Wise noted that radar-deception techniques such as Doppler spoofing can make aircraft appear to be at false distances or velocities, potentially explaining some of the “impossible” radar contacts reported by military operators.

The U.S. military’s own classified programs could also generate UAP reports. Aircraft testing at restricted ranges, high-altitude reconnaissance platforms, and classified drone programs could all produce observations that would appear anomalous to personnel not briefed on the programs.

Opposing Perspective

Garry Nolan, a Stanford University professor of pathology and one of the most cited immunologists in the world, has spent over a decade investigating anomalous materials and the biological effects reported by UAP witnesses. His work began with the CIA, analyzing brain scans of individuals who reported exposure to unexplained phenomena, some overlapping with what became known as Havana Syndrome. Nolan found hypertrophy of the caudate-putamen in over 100 MRI scans of individuals who reported UAP encounters. He has since used high-precision mass spectrometry to analyze metallic fragments from alleged UAP incidents, including samples supplied by Jacques Vallée from a 1950s Brazilian event. Some samples showed unexpected isotopic ratios that would be extremely expensive to produce deliberately. Nolan presented these findings at the SOL Foundation, which he co-founded. His talk on the material science of UAP is embedded below.

Astronomer Beatriz Villarroel leads the Vanishing and Appearing Sources during a Century of Observations (VASCO) project. In 2025, she published two peer-reviewed papers that are directly relevant to the scientific investigation of anomalous observations.

The first, published in Scientific Reports (a Nature journal), found correlations between transient objects appearing on 1950s Palomar sky survey photographs and nuclear weapons testing periods, with statistical significance at approximately 22 sigma. The second, published in the Publications of the Astronomical Society of the Pacific, presented evidence of coordinated transient events in pre-satellite-era sky survey photographs that are not easily explained by gravitational lensing, gamma ray bursts, or plate defects.

Villarroel’s work does not claim these objects are extraterrestrial, but notes that conventional explanations for the observed patterns have not been established. An interview with Villarroel and journalist Ross Coulthart discussing the significance of these publications is available below.

The Planetary Society, in a March 2025 analysis, noted that “most cases end up being things like balloons and optical illusions” but acknowledged that “scientists are eager to look into any mystery they think might lead to cool new discoveries.” The organization’s position is that UAP investigation should continue with proper scientific methodology, even if most cases turn out to have conventional explanations.

A Nature Scientific Reports study published in December 2023 found correlations between UAP sighting frequency and factors including tree cover, light pollution, and proximity to airports , environmental variables that influence both the likelihood of seeing a conventional object and the likelihood of misidentifying it. The study did not reach conclusions about the nature of unexplained cases.

AARO itself has acknowledged that a small number of cases remain unresolved. The FY2024 report states that AARO continues to investigate cases where data is sufficient to support further analysis. The office’s position is not that all UAP are prosaic, but that most are, and that rigorous investigation of the remaining cases requires better data and methodology.

More UAP Science Analysis

VFX artists at Corridor Crew analyze the Pentagon’s UAP videos and demonstrate how camera artifacts, parallax, and compression can make ordinary objects appear anomalous.

Astrum examines UAP evidence and explains how to separate factual analysis from speculation in UFO reporting.

What the Research Shows

Across 75 years of official investigation, the pattern is consistent. Project Sign (1947-1949), Project Grudge (1949-1952), Project Blue Book (1952-1969), the Condon Committee (1966-1968), and AARO (2022-present) have all concluded that the vast majority of UAP reports are attributable to conventional phenomena. The specific explanations vary by era , misidentified aircraft dominated Cold War reports, while balloons and drones dominate modern ones , but the underlying conclusion remains the same: most sightings have scientific explanations. The natural causes behind UFO sightings range from atmospheric phenomena to optical illusions to simple misidentification of familiar objects. Common natural causes UFO sightings include planets, balloons, drones, and atmospheric phenomena.

The challenge in UAP investigation has never been identifying cases with conventional explanations. It has been obtaining sufficient data to resolve cases that initially resist explanation. The 2024 AARO report specifically notes that many unresolved cases remain unresolved not because they exhibit extraordinary characteristics, but because the available data is insufficient to reach any conclusion at all.