Could 3I/ATLAS Be More Than Just a Comet? New Data Sparks Intriguing Possibilities
7-minute read
Just released data from the Minor Planet Center [https://www.minorplanetcenter.net/dbsearch/showobject?utf8=%E2%9C%93&objectid=3I] and NASA’s Jet Propulsion Laboratory [https://ssd.jpl.nasa.gov/tools/sbdblookup.html#/?sstr=3I%2FATLAS&view=OPC] sheds new light on the interstellar visitor 3I/ATLAS [https://en.wikipedia.org/wiki/3I/ATLAS] after its closest approach to the Sun (perihelion) on October 29, 2025. This fresh information, covering October 31 to November 4, reveals some fascinating changes compared to earlier observations from October 5–8.
But here's where it gets controversial... While 3I/ATLAS appears to have brightened significantly (by a factor of 5) in the Green-band wavelength [https://www.annualreviews.org/content/journals/10.1146/annurev.astro.41.082801.100251], its non-gravitational acceleration has decreased by a third. This reduction falls within expected margins of error, and the detection is now even more solid, reaching 3.7 standard deviations.
What does this mean? The non-gravitational acceleration, measured at a distance of 1.38 astronomical units (AU) from the Sun (roughly 206 million kilometers), exhibits two components within the object's orbital plane but none perpendicular to it. These components, following an inverse square law based on distance from the Sun, are:
- Radial acceleration away from the Sun: 1.1x10^{-6} AU per day squared
- Transverse acceleration relative to the Sun's direction: 3.7x10^{-7} AU per day squared
And this is the part most people miss... According to the principle of momentum conservation [https://avi-loeb.medium.com/afterthoughts-on-the-non-gravitational-acceleration-of-3i-atlas-at-perihelion-97c609e24fc6], this acceleration implies that 3I/ATLAS must have shed a measurable portion of its mass, akin to a rocket expelling gas. My calculations [https://avi-loeb.medium.com/afterthoughts-on-the-non-gravitational-acceleration-of-3i-atlas-at-perihelion-97c609e24fc6] suggest that the mass loss during perihelion passage is proportional to the acceleration and the time spent near the Sun.
Considering the perihelion distance and speed, this translates to a potential mass loss of around 13% if the gas ejection speed is similar to that of a typical comet (around 300 meters per second). However, if 3I/ATLAS possesses a technological propulsion system, it could expel gas at much higher speeds, significantly reducing the required mass loss. The object's dramatic brightening and blue hue near perihelion [https://arxiv.org/pdf/2510.25035] could be attributed to either cometary outgassing and CO+ emission [https://avi-loeb.medium.com/3i-atlas-rapidly-brightens-and-gets-bluer-than-the-sun-near-perihelion-3bf100df8390] or a hot engine with minimal mass loss.
A Crucial Test Ahead: The coming weeks will be pivotal. If 3I/ATLAS is a natural comet, it should be surrounded by a substantial gas cloud containing at least 13% of its original mass. This cloud should be far more prominent than what was observed between July and September, when no non-gravitational acceleration was detected [https://arxiv.org/pdf/2509.21408]. Spectroscopic observations by the Webb telescope in December could reveal the composition of this cloud, providing insights into the object's interior, not just its surface.
However, if 3I/ATLAS lacks a significantly larger gas cloud post-perihelion compared to pre-perihelion, its recent acceleration likely stems from a source other than cometary evaporation.
The Anomalies Pile Up: 3I/ATLAS continues to defy easy explanation with a string of peculiarities:
- Retrograde Orbit: Its path is aligned within 5 degrees of the ecliptic plane, a highly unlikely occurrence (0.2% chance) [https://arxiv.org/pdf/2507.12213].
- Sunward Jet: It exhibited a sunward-pointing jet (anti-tail) during July and August 2025, unlike typical comets [https://arxiv.org/pdf/2509.07771].
- Massive and Fast: Its nucleus is a million times more massive than 'Oumuamua [https://en.wikipedia.org/wiki/1I/%CA%BBOumuamua] and a thousand times more massive than Borisov [https://en.wikipedia.org/wiki/2I/Borisov], yet it moves faster than both, with a combined probability of less than 0.1% [https://iopscience.iop.org/article/10.3847/2515-5172/adee06/ampdf, https://arxiv.org/pdf/2509.21408].
- Strategic Timing: Its arrival was precisely timed to pass close to Mars, Venus, and Jupiter while remaining unobservable from Earth at perihelion, a 0.005% probability [https://arxiv.org/pdf/2507.12213].
- Unusual Composition: Its gas plume contains significantly more nickel than iron, resembling industrially produced alloys, and a nickel-to-cyanide ratio far exceeding known comets, including Borisov (likelihood < 1%) [https://arxiv.org/pdf/2510.11779].
- Low Water Content: It contains only 4% water by mass, unlike typical comets [https://iopscience.iop.org/article/10.3847/2041-8213/ae0647/pdf].
- Extreme Polarization: It exhibits extreme negative polarization, unprecedented for comets, including Borisov (likelihood < 1%) [https://arxiv.org/pdf/2509.05181].
- Wow! Signal Connection: Its trajectory aligns within 9 degrees of the famous 'Wow! Signal', a 0.6% probability [https://avi-loeb.medium.com/was-the-wow-signal-emitted-from-3i-atlas-d18d4f0d1f1e].
- Unprecedented Brightening: It brightened faster than any known comet and appeared bluer than the Sun near perihelion [https://arxiv.org/pdf/2510.25035v1].
- Mass Loss Mystery: While its non-gravitational acceleration suggests significant mass loss (around 1/6th of its mass), preliminary post-perihelion images show no evidence of this so far [https://avi-loeb.medium.com/afterthoughts-on-the-non-gravitational-acceleration-of-3i-atlas-at-perihelion-97c609e24fc6].
A Thought-Provoking Email: This morning, I received a thought-provoking email from Dr. Sukanto Bhattacharya of Deakin University, Australia. He expresses his appreciation for my writings on 3I/ATLAS and shares his concerns about the current state of scientific discourse. Dr. Bhattacharya draws a parallel between the 'scientific power lobbies' of today and the church of the Middle Ages, arguing that dissenting ideas often face resistance akin to the persecution faced by Galileo. He commends my ability to withstand such attacks and engage in rigorous intellectual debate. His upcoming book, 'Brainmaker — coevolution of human and synthetic intelligence', explores these themes further.
Food for Thought: 3I/ATLAS continues to challenge our understanding of interstellar objects. The upcoming observations will be crucial in determining its true nature. Are we witnessing a natural comet with unusual characteristics, or something entirely different? The scientific community must remain open to all possibilities and embrace the spirit of inquiry that drives true discovery. What do you think? Is 3I/ATLAS just a peculiar comet, or could it be something more?
