AARO is not saying it's that particular type of balloon. Their assessment is only with "moderate confidence" and some of it seems a bit of a stretch.
They also try to explain how it would be lit underneath if it were not self-illuminated:
It appears to be looking down at the object from above (ocean background), which suggests the sun near the horizon, but then that's at odds with the "earth shine" theory.
Time of day illumination analysis might be something useful to put into Sitrec. But rather tricky with no real data here.
Overall, I agree a balloon is most likely, but beyond that there's not enough data to make a firm determination.
So they say it's uniformly black/grey in visible light (EO) video, and they attribute the difference in the IR image to differing hemisphere.Although the pilot described the object as uniformly gray in the visible spectrum (it appears
uniformly black from the viewing angle in the EO image), the magnified infrared image shows
the object had a strong contrasting signature in the infrared spectrum. This contrast suggests
either a temperature/emissivity difference or a reflectivity difference between its two
hemispheres. AARO identified a commercial lighting balloon (see Figure 1C), which is a close
visual match to the object in the zoomed-in infrared image (see Figure 1A). Commercial helium
balloons such as these are often large and available in many shapes — including ellipses,
spheres, and cylinders — and are used for outdoor lighting at special events, construction sites,
and movie sets. Although these balloons are available in solid colors, some models have distinct
black and white hemispheres. The upper black hemisphere is lined with reflective material to
direct the light downward through the white hemisphere. AARO conducted extensive testing
using one of these balloons and found it could replicate some aspects of the pilot’s account.
But the compelling-looking comparison here is A vs. C. A is IR, and C is visible light.Figure 1: Comparison of reported UAP (A: Infrared image of reported object, B: Electro-optical image
of reported object, and C: Image of a commercial LTA lighting system) (Photo credit: AARO)
They also try to explain how it would be lit underneath if it were not self-illuminated:
I have never heard of "Earth Shine" outside of the context of the Moon at night (or during a total eclipse). But then the IC partner seems to think it's direct illumination. Their diagram is of little help:
It is also plausible that
the sun angle at the time of day of the event, when plotted with the EO/IR sensor’s viewing
angle, illuminated the bottom half of the balloon — from the pilot’s perspective — while the top
would appear dark, shaded, and cold (See Figure 3).
• (U) Due to the angle of the sun and the altitude of the object, a meteorological or Mylar
balloon likely would also present in a similar fashion on an EO/IR image. The highly
reflective surface of a Mylar balloon in infrared would exaggerate the perceived
illumination effect.
(U) AARO’s IC partner on this case assesses with high confidence that the object was not
exhibiting anomalous characteristics based on the available data and its reconstruction of the
event. Available data included the altitude, geocoordinates of the object, the aircraft viewing
angle and heading, as well as the sun geometry at the time of the observation.
• (U) Based on reconstruction of the event, to include the viewing angle of the EO/IR sensor
that took the zoomed-in image, the sun would have illuminated the bottom hemisphere in
a manner consistent with the IR image (see Figure 3). The orange-red color at the center
of the bottom half of the object could be explained by the sun glint off the object as the
pilot observed it, thus causing the appearance of the orange-red colors on the balloon.
(U) The S&T partner assesses that the image is consistent with a Mylar balloon as viewed
from above where the bottom is illuminated with light reflected from the clouds or the
earth. This effect is known as “Earth shine.”
It appears to be looking down at the object from above (ocean background), which suggests the sun near the horizon, but then that's at odds with the "earth shine" theory.
Time of day illumination analysis might be something useful to put into Sitrec. But rather tricky with no real data here.
Overall, I agree a balloon is most likely, but beyond that there's not enough data to make a firm determination.
