Updating the Loeb Classification Scale of 3I/ATLAS
December 21, 2025
The Loeb scale ranks interstellar objects on a scale between 0 for natural icy rocks (comets or asteroids) to 10 for alien technology that is a potential threat to humanity.
The Loeb classification was quantified in two peer-reviewed publications, available here and here. This quantitative classification was expanded a week ago in a new paper here to a formalism that evolves the ranking of an interstellar object as new data about it comes in.
Shortly after 3I/ATLAS was discovered in July 2025, I ranked it as 4 on the Loeb Scale.
When asked to update the rank recently, I declined to do so until new data from the period bracketing its closest approach to Earth is publicly released and analyzed.
The new data release may not conclude before 3I/ATLAS arrives closest to Jupiter on March 16, 2026.
In a recent interview on NewsNation (available here), I was asked by Elizabeth Vargas to clarify my standpoint about the nature of 3I/ATLAS.
In response, I repeated what I said before — that 3I/ATLAS is most likely a natural object. This response was highlighted as news but it is not so.
I expressed the same standpoint as early as July 2025. This is evident from the Conclusions section of my peer-reviewed publication here, as well as from the content of many of my essays — such as the essay posted here on July 27, 2025.
In answer to a reporter’s question, posted here on October 29, 2025: “Do we know about whether it really is a natural comet or something else?”, I responded: “3I/ATLAS is most likely a comet of natural origin, but there are 8 anomalies that endow it with a rank of 4 on the Loeb scale.”
Back on October 29, I flagged 8 anomalies of 3I/ATLAS, but by now the number grew to 15 — as listed here.
My standpoint all along was that we must consider the technological interpretation seriously because of the possibility of a black swan event with low probability and huge implications to humanity.
Following the dismissal of black swan events on September 11, 2001 and October 7, 2023, intelligence agencies worldwide revised their practices and they now attempt to collect as much data as possible on low-probability events with major implications.
This echoes the philosophical rationale in Pascal’s Wager.
Scientists are not used to a `black swan mindset’, because their research rarely has immediate and major implications to society.
Having an unknown visitor from the cosmic street to our backyard requires that we stay alert to the risk from it entering our home, especially when its tail is coming from its forehead rather than its back — as is the case in common street cats.
Nothing has fundamentally changed about my standpoint as of yet. The NewsNation interview reflected my previous arguments. The real update will come as a result of the analysis of new data in the coming months.
The most revealing data will likely involve the spectrum of the anti-tail jet, which stretches across a million kilometers towards the Sun in the latest images.
Measuring the speed and composition of the anti-tail would distinguish between an origin from the sublimation of natural pockets of ice on the surface of a rock versus a technological thruster.
In the first case, we should find CO2, CO and H2O gas moving at a maximum speed of hundreds of meters per second, whereas in the second case the jet composition might appear to be anomalous and the exhaust speed could be orders of magnitude larger.
And of course, any release of smaller objects near Jupiter, and the detection of artificial lights or unexpected maneuvers, might also constitute a technological signature.
But in the absence of a clear technological signature, I will revise my Loeb Scale rank downward.
Science is done in a more reliable fashion than the quality of news reports. Stay tuned.
https://avi-loeb.medium.com/updating-the-loeb-classification-scale-of-3i-atlas-eb495684462e
https://usaherald.com/avi-loeb-pauses-his-interstellar-classification-scale-as-3i-atlas-moves-toward-jupiters-gravitational-gate/
https://www.ibtimes.co.uk/what-happened-when-3i-atlas-approached-earth-heartbreak-looms-astronomers-1764690
https://wtop.com/the-space-place/2025/12/cosmic-trifecta-winter-solstice-meteors-from-the-little-bear-alien-comet-passes-by-earth/
https://www.youtube.com/watch?v=j1h_3Jsy6kw (John Lenard Walson: 🚀 @ 3I/ATLAS #3i/ATLAS)
https://www.youtube.com/watch?v=sLjxevbmSSw (UFOvni2012: 3I/Atlas: Last Friday, December 19th, the long-awaited day arrived.)
https://x.com/StefanBurnsGeo/status/2002919037261717779
https://x.com/AJamesMcCarthy/status/2002881824431935588
https://x.com/AJamesMcCarthy/status/2002537146943717564
https://x.com/forallcurious/status/2003070930696974434