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Interstellar Comet 3I/ATLAS Shows "Extreme Negative Polarization". What Does That Mean?
IFL Science ^ | October 06, 2025 | James Felton

Posted on 10/06/2025 11:33:25 AM PDT by Red Badger

According to the team the polarimetric behavior is "significantly different from all known comets (either interstellar or bound to our Solar System)".

3I/ATLAS imaged by NASA’s Spectro-Photometer for the History of the Universe, Epoch of Reionization and Ices Explorer (SPHEREx).

Image credit: NASA/SPHEREx.

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Ateam of astronomers have presented the first polarimetric observations of interstellar comet 3I/ATLAS, finding that it has extreme negative polarization.

On July 1, 2025, astronomers spotted an object moving through the Solar System at nearly twice the velocity of previous interstellar visitors ‘Oumuamua and Comet Borisov. The object was confirmed to be an interstellar comet with its own dusty coma, and suspected to be far larger than the previous two, with a estimated nucleus (the rocky part of the comet, excluding its coma) of around 5.6 kilometers (3.5 miles), and a possible "anomalous" mass of over 33 billion tons.

VIDEO AT LINK...................

The astronomical community continued to track the object, known to be a comet due to outgassing as it has approached closer to the Sun, as it made its way through the Solar System. Unfortunately, and after potentially being hit by a coronal mass ejection, it has now vanished from our view and won't be back in sight until later this year.

Part of these observations have been imaging and spectroscopy of the object, revealing that it has a green tinge and some interesting chemistry going on, and its distinctive coma. But polarimetry, or measuring the rotation of plane-polarized light, can tell us a lot about about near and distant objects too, allowing astronomers to gain data on, for example, the size, shape, and orientation of dust particles surrounding a comet.

"Light is a wave consisting of a coupled oscillating electric and magnetic fields which are orthogonal to each other in a plane that is perpendicular to the direction of propagation of the wave (in vacuum)," Harvard astronomer Avi Loeb, who was not involved in the new research, explains in a blog post.

"The polarization of the wave corresponds to different modes of field oscillations. For linear polarization, the electric and magnetic fields oscillate along a single direction, whereas for circular polarization – the fields rotate at a constant rate in their plane as the wave travels, either in the right-hand or in the left-hand direction."

"The level of polarization displayed by an object which scatters sunlight like 3I/ATLAS, reflects asymmetries in its global shape or its corpuscular composition. The polarization depends on the phase angle at which the 3I/ATLAS is observed, namely the angle between the Sun-3I/ATLAS axis and the 3I/ATLAS-observer axis."

Measuring the degree of polarization can tell us a lot about 3I/ATLAS, and other, more local, comets. Astronomers measure the degree of polarization, as well as whether it is negative or positive.

"The degree of linear polarization Pr of sunlight scattered by cometary dust particles is measured as the difference between the fluxes perpendicular and parallel to the scattering plane (Sun-comet-observer plane), normalized by their sum, and is highly sensitive to the solar phase angle α (Sun-comet-observer angle)," the team explains in their paper, currently posted as an unreviewed preprint.

"Because of this definition, polarization is positive when the polarization direction is oriented perpendicular to the scattering plane, and negative when parallel."

Comets we have observed so far can vary in their polarization based on their distance from the Sun, and the distance of the comet from our telescopes, but there are still trends within this. Generally comets fit into one of two categories (high polarization comets and low polarization comets) though there are a few oddballs out there, like Hale-Bopp, which are outliers for their unusually high polarization.

"3I is characterized by an extremely deep and narrow negative polarization branch, with parameters Pmin = −2.77 ± 0.11%, αmin = 6.41±1.27◦, α0 = 17.05±0.12◦, and h = 0.40±0.02% deg−1," the team explains in their paper.

"This polarimetric behaviour is significantly different from all known comets (either interstellar or bound to our Solar System), not fitting into either the high or low-polarization comet categories, nor that of the unique category occupied by just Hale-Bopp and 2I."

The team suggests that the comet has more in common with trans-Neptunian objects (TNOs), minor planets and smaller objects that orbit the Sun beyond Neptune, and Centaurs.

"While 3I’s inversion angle resembles that of rare F-type asteroids and cometary nuclei, the depth of its negative polarization branch is almost twice as large. Extrapolation to very small phase angles indicate a steep polarization slope between phase angles 0–2°, reminiscent of certain small TNOs and Centaurs," the team writes. "While this finding is tentative due to a lack of data at small phase angles, it is consistent with the red spectral slope and evidence of water-ice detections in various independent studies."

Further observations of the object are needed, but, of course, it is currently out of view.

"Imaging confirms a diffuse coma present from our earliest observations, though no strong polarimetric features are spatial resolved," the team adds in a statement. "These findings may demonstrate that 3I represents a distinct type of comet, expanding the diversity of known interstellar bodies."

The paper has been submitted to The Astrophysical Journal Letters but is currently unreviewed. It has been posted to preprint server arXiv.


TOPICS: Arts/Photography; Astronomy; History; Science; UFO's; Weird Stuff
KEYWORDS: 3iatlas; astronomy; aviloeb; comet; harvard; interstellar; science
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To: Red Badger
Shows "Extreme Negative Polarization". What Does That Mean?


21 posted on 10/06/2025 11:59:04 AM PDT by Opinionated Blowhard (When the people find that they can vote themselves money, that will herald the end of the republic.)
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To: Red Badger

Hopefully it means THE END. And it couldn’t come too soon!


22 posted on 10/06/2025 12:10:06 PM PDT by montag813
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To: decal

Beam me down STAT!.


23 posted on 10/06/2025 12:10:15 PM PDT by rktman (Destroy America from within? On hold! Enlisted USN 1967 proudly. 🚫💉! 🇮🇱🙏! Winning currently!)
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To: tet68

“Schrodinger says it can be a wave AND a particle...”

Newton. Shrodinger just developed the equations.


24 posted on 10/06/2025 12:10:48 PM PDT by TexasGator (The 750 hp Florida Gnat)
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To: montag813

Oddly enough, I am currently reading “When Worlds Collide” and “After Worlds Collide”....................


25 posted on 10/06/2025 12:11:30 PM PDT by Red Badger (Homeless veterans camp in the streets while illegals are put up in 5 Star hotels....................)
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To: Red Badger

>> “After Worlds Collide”....................

There’s enough left to write a book about??!?


26 posted on 10/06/2025 12:15:36 PM PDT by Nervous Tick (Hope, as a righteous product of properly aligned Faith, IS in fact a strategy.)
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To: Red Badger

It’s got negative vibes man


27 posted on 10/06/2025 12:16:50 PM PDT by nevadapatriot
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To: tet68

Yes, but why does that box in his office smell so bad?


28 posted on 10/06/2025 12:17:29 PM PDT by Empire_of_Liberty
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To: Red Badger

Might as well read “Worlds in Collision” as well. LoL


29 posted on 10/06/2025 12:17:50 PM PDT by montag813
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To: Red Badger

Always with the negative waves, Moriarty, always with the negative waves.


30 posted on 10/06/2025 12:17:51 PM PDT by HartleyMBaldwin
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To: Red Badger

Heck, Trekies know this...it’s what happens when one saves a situation by “reversing the polarity”


31 posted on 10/06/2025 12:18:17 PM PDT by Da Coyote
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To: dayglored
But most troubling.... the CME turned it into an InterStellar Monster, AND IT'S HUNGRY!!

I keep telling you people the Fantastic Four movie wasn't about entertainment - it was the notice.

Galactus

32 posted on 10/06/2025 12:20:44 PM PDT by MikelTackNailer (Free compassion and beer tomorrow.)
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To: Nervous Tick

There were two alien rogue planets, Neptune sized Bronson Alpha, and Earth sized Bronson Alpha.

Bronson Alpha smashed the Earth and destroyed it, then continued on it’s way out of the solar system back into the void of space.

Different national groups managed to build space ships to make it safely to the new planet, Bronson Beta, which took up Earth’s position, though in a very elongated orbit.

Even before the final encounter, earth based telescopes saw what were the remains of cities on the new planet. The beings that had lived on it before it was torn away from its sun, perhaps a billion years before coming to ours apparently were aware of their fate, and could do nothing about it....................


33 posted on 10/06/2025 12:22:07 PM PDT by Red Badger (Homeless veterans camp in the streets while illegals are put up in 5 Star hotels....................)
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To: Red Badger
It's the Vogons come to make way for the new intergalactic freeway.
Vogons are very negative.
34 posted on 10/06/2025 12:23:24 PM PDT by TangoLimaSierra (⭐⭐To the Left, the Truth is Right Wing Violence⭐⭐)
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To: montag813

“The End”
.
The Doors did a Humble
Little Song about that.
.
Hope everyone is Prepared!


35 posted on 10/06/2025 12:31:24 PM PDT by Big Red Badger (ALL Things Will be Revealed !)
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To: Red Badger

David Drew: 3I/Atlas is an Electric Comet in Real Time | Thunderbolts

https://www.youtbe.com/watch?v=2EvHkhc2bdw


36 posted on 10/06/2025 12:42:04 PM PDT by pa_dweller (Projection, prosecution, prevarication and party over country: That's the Democrat brand)
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Wooo woooo wooo…twilight zone stuff🤡🤡🤡


37 posted on 10/06/2025 12:46:54 PM PDT by TnTnTn
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To: decal

It needs to find a charging station.


38 posted on 10/06/2025 12:58:27 PM PDT by SaxxonWoods (Annnd....TRUMP IS RIGHT AGAIN.)
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To: Red Badger

39 posted on 10/06/2025 12:59:50 PM PDT by Sirius Lee ("Never argue with a fool, onlookers may not be able to tell the difference.”)
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To: Sirius Lee
"Yeah, reverse polarity!"


40 posted on 10/06/2025 1:01:02 PM PDT by Sirius Lee ("Never argue with a fool, onlookers may not be able to tell the difference.”)
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