A groundbreaking analysis of the Hubble Space Telescope image of the interstellar object 3I/ATLAS, co-authored by scientists including Eric Keto, has unveiled striking features in the observed glow of scattered sunlight around the object.
This glow, which extends sunward, is found to be twice as long towards the Sun compared to its width or length in directions that are perpendicular or opposite to the Sun’s position.
Interestingly, the observed glow forms an anti-tail, contrary to the typical cometary behavior where dust particles reflect light away from the Sun, creating tails that point in the opposite direction.
The authors point out that the anti-tail phenomenon of 3I/ATLAS is particularly remarkable as it reveals a factor of two extension in an unfavorable geometric projection.
When the Hubble image was captured on July 21, 2025, the alignment of 3I/ATLAS with Earth was misaligned by only 10 degrees from the Sun, suggesting we are observing the glow nearly edge-on.
Statistically, this means with a correction factor of 5.76, if a spacecraft were to hover above the elongated glow, it could see it extending ten times farther sunward than its width or tail.
This significant elongation has not been documented in any previous scientific literature, underscoring the unique traits of 3I/ATLAS.
The authors attribute the scattered sunlight dynamics around 3I/ATLAS to ice fragments rather than the more commonly assumed refractory dust.
The fragments, vaporized by sunlight, are launched from the sunward side of the object, allowing the largest ice pieces to survive a greater distance toward the Sun than sideways or backward.
Despite potential alternative explanations for this phenomenon, the evidence suggests that the excessive glow extension toward the Sun is indeed unprecedented.
In a recent interview titled ‘Question Everything’ aired on CBS News, the co-author shared insights into 3I/ATLAS and its five peculiar anomalies.
First, the interstellar object’s retrograde trajectory is intriguingly aligned with the ecliptic plane of Solar System planets to within 5 degrees, an alignment calculated to have a probability of occurrence of just 1 in 500.
Second, field studies have established an upper limit on the object’s nucleus diameter of 46 kilometers—potentially making it a million times more massive than the interstellar comet 2I/Borisov.
On October 3, researchers anticipate that the HiRISE camera aboard the Mars Reconnaissance orbiter will achieve remarkable resolution, capable of imaging 3I/ATLAS with a resolution of 30 kilometers, allowing for a more precise measurement of its nucleus.
Additionally, for several months after its discovery, 3I/ATLAS exhibited a glow that extended toward the Sun, contrasting with typical comet behavior which usually shows glow extending away from the Sun.
This unprecedented anti-tail observation reiterates the need for a deeper understanding of its composition and behavior.
The gas plume surrounding 3I/ATLAS has also been characterized scientifically, revealing that it comprises predominantly of carbon dioxide—87% by mass, along with traces of carbon monoxide—9%, and water—around 4%.
Notably, the gas plume features both nickel without iron and cyanide, both of which increase sharply as 3I/ATLAS approaches the Sun, suggesting unique chemical processes related to its icy constituents.
Lastly, one of the most intriguing findings relates to the polarimetric behavior of 3I/ATLAS: it displays an extreme negative polarization of -2.77 percent along with a low inversion angle of only 6.41 degrees.
This polarimetric signature is significantly different from all known comets, whether they are interstellar or bound to our Solar System, marking a first in astronomical observations.
The combination of these five anomalies supports the hypothesis that 3I/ATLAS may possess unique characteristics that transcend previous knowledge about such celestial objects.
Historically, scientific discussion has often leaned toward viewing celestial phenomena under traditional doctrines, as echoed in Ecclesiastes 1:9, which states, ‘What has been will be again; what has been done will be done again; there is nothing new under the sun.’
However, the evidence surrounding 3I/ATLAS urges scientists to gather as much observational data as possible, as its passage near the Sun may reveal unexpected discoveries.
In considering the totality of these new findings, it is increasingly plausible that traditional perspectives on celestial phenomena may be flawed, and thus, advocates urge continuation in questioning established knowledge.
image source from：avi-loeb
