Lightning flash or UFO: the sprite theory and AARO's new report
For years, a Tel Aviv physicist has explained some UFO sightings as flashes of a rare atmospheric phenomenon, the sprite. According to a report released this summer by AARO, the Pentagon's UAP office, every one of the 370 cases closed in fiscal year 2025 received a mundane explanation, while the investigation of nine cases is still ongoing.
Sprites are reddish electrical discharges lasting a fraction of a second that flash at altitudes of 50 to 90 kilometers above thunderclouds when a particularly powerful lightning bolt alters the electric field of the upper layers of the atmosphere. Colin Price, head of the Department of Geophysics and Planetary Sciences at Tel Aviv University, suggested as early as 2009 that this phenomenon, rather than alien craft, could be behind some UFO sightings. His research group also captured images in which the sprites were arranged in a circle, like the candles on a birthday cake; some of their columns reached 24 kilometers high, and the clusters could be as much as 70 kilometers wide.
For a long time, science did not even know about the phenomenon, until in 1989, while testing a high-sensitivity camera intended for astrophotography, researchers at the University of Minnesota accidentally recorded two vertical flashes of light above a distant storm. Since then, sprites have belonged to the broader family of atmospheric light phenomena known as transients, which also includes rings of light expanding in the ionosphere, the so-called elves, and blue jets shooting upward from the tops of clouds. Since 2018, an instrument called ASIM, installed on the International Space Station, has been continuously monitoring them from above, with the involvement of the University of Valencia.
It is important to correct a frequently cited but false claim: sprites do not occur exclusively in winter or in the Northern Hemisphere; they appear above storms all over the planet and are more frequent in summer, during stronger thunderstorms. Price's research actually concerned a narrower subtype, the so-called winter sprites, which are linked to winter storms forming in the Eastern Mediterranean, off the coast of Israel, and are indeed characteristic of the Northern Hemisphere winter.
The reason the phenomenon can be mistaken for a UFO is that it is so fast and faint that the human eye can barely perceive it: it mostly appears only out of the corner of the eye, on a very dark night, above a distant storm lurking on the horizon. This brief flash, which appears and then vanishes above the clouds, can easily be confused with the lights described in reports as moving without gravity.
What does the Pentagon's latest report say, and what remains an open question?
AARO (All-domain Anomaly Resolution Office), the UAP office of the U.S. Department of Defense, released its report for fiscal year 2025 this summer. According to it, 319 new reports of unidentified anomalous phenomena were received during the period, and a mundane explanation was found for every one of the 370 closed cases: balloons, birds, drones, floating debris and, increasingly often, reflections from satellites were identified as causes, the latter explaining 42 cases reported by civilian pilots. According to the report, the analysis of nine cases is still in progress, and the document once again denied that the U.S. government is keeping the wreckage of extraterrestrial spacecraft.
However, the sprite theory and AARO's statistics do not fully settle the question. Sprites do not explain lights seen in clear, cloudless skies or objects appearing on military radar; other mundane candidates are usually considered for these, such as the strikingly bright planet Venus, Starlink satellites passing in single file, or high-altitude weather balloons still reflecting sunlight, which appear against a sky that is already darkening below. According to the report, the small fraction that remains unexplained is mostly due to poor-quality data: a blurry recording, a single witness, or a photograph with no reference point for estimating distance.
The sober take
According to physicist Colin Price, some UFO sightings may be caused by sprites flashing in the upper layers of the atmosphere, and according to AARO's official report, the vast majority of the cases examined have a mundane explanation, such as balloons, drones or reflections of satellite light.
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