Mt-Etna-Object_Case_Resolution.pdf

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All-domain Anomaly Resolution Office 
U.S. Department of Defense 
Case: “Mt. Etna Object” 
Case Resolution | 28 April 2025 
Case Synopsis 
Location:  Mt. Etna, Italy 
Date:  December 2018 
Object Altitude (reported):  500 feet 
Object Altitude (assessed):  15,000 feet 
Object Speed (reported):  345 mph 
Object Speed (assessed):  24 mph  
Object Shape (reported):  Round 
Object Shape (assessed):  Spherical 
Reporter:  U.S. Military UAS operators 
Data Type:  Infrared 
Reported Behavior:  An object moving at 
high speeds through Mt. Etna’s ash plume. 
Assessed Beha…

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The object did not exhibit anomalous speeds or other behavior exceeding known state-of-
the-art performance characteristics. It did not pass through the volcano’s ash plume.
Performance Characteristics 
Object Speed: AARO assessed that the object’s speed was approximately 39 kph (24 mph), 
moving generally west-to-east, consistent with wind speed and direction. The object’s apparent 
high speed is attributable to motion parallax. Motion parallax is an optical effect that induces an 
observer to perceive that a stationary or slow-moving object is moving much faster than its 
act…

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Figure 2: AARO’s top-down reconstruction of the event depicting the object’s distance from the 
UAS platform. (not to scale) 
Observable Characteristics and Attribution 
Size and Shape: AARO employed pixel examination to conclude with moderate confidence that 
the object was spherical. Its approximate diameter was 0.3 meters (1 foot). (Figure 3)  
Attribution: Due to the object’s size and performance characteristics, AARO assesses with 
moderate confidence that the object is a balloon.  
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Figure 3: The object at a higher magnification (0749Z) and enhanced using post-processing 
tools (0753Z). The object is spherical with an approximate diameter of one foot. 
Data Quality and Methodology: AARO assesses that the sensor data associated with the event 
provides sufficiently detailed information to resolve this case with moderate confidence. 
However, sensor limitations and atmospheric turbulence constrain the modes of rigorous analysis 
that can be applied to identify the object conclusively. 
Sensor Effects and Limitations: SWIR sensor…

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These factors likely influenced the reporter’s perceptions of the event, leading to unreliable 
initial conclusions about the object’s speed and performance characteristics. AARO cautions that 
the SWIR sensor’s image data should not inform any conclusion of the object’s performance 
characteristics because of the significant limitations imposed by atmospheric turbulence, post-
processing effects, and contrast stretching. These effects produce visual artifacts such as 
flickering, pulsating, and luminosity differences, significantly reducing the reliability of 
t…