Goodbye! Comet 3I/ATLAS

…as you leave behind a silent triumph for science

 

“A lie can travel halfway around the world before the truth puts on its shoes”

 - Anon

Current location of comet 3I/ATLAS

This is the fourth guest article from Ilavenil T under my banner.  She follows up on her previous one (see here) on how pseudoscientific claims can be put under the microscope with Carl Sagan’s Boloney Kit, with particular reference to solar system’s third interstellar visitor comet 3I/ATLAS, and attempts to separate the grains of sensible science from the chaff of pseudoscience.    

Ilavenil T

Comet 3I/ATLAS was the third (known) interstellar object to enter our Solar System, and after months of excited observations from the astronomical community, is now on the way out of the Solar System. Interstellar objects like these are akin to the storytellers who travelled the land in every culture – teaching lessons and moving on! Farewell to the visitor who brought us so much knowledge! What happened as expected and what didn’t? This article is a look at the scientific and pseudoscientific claims and insights.

Observations of Comet 3I/ATLAS

From the time 3I/ATLAS was discovered, and its rare interstellar nature recognized, there has been international collaboration between observatories and institutions on an unprecedented scale to extract as much information as possible about this extraordinary visitor amongst us, visible only through large telescopes. A similar effort was made for the earlier interstellar discoveries, 1I/Oumuamua and 2I/Borisov. 

Here’s a representative list of the observatories and organizations which followed Comet 3I/ATLAS in its eccentric path ^[2]: 

Survey/Discovery Organizations

·      Asteroid Terrestrial-impact Last Alert System (ATLAS)

·      NASA

·      International Astronomical Union's Minor Planet Center (MPC)

Observatories and Telescopes

·      ATLAS survey telescope at Río Hurtado, Chile (observatory code W68)

·      Gemini North & South telescopes

·      Zwicky Transient Facility (ZTF, observatory code I41)

·      Deep Random Survey (X09) at Chile

·      Lowell Discovery Telescope (G37) at Arizona

·      Canada–France–Hawaii Telescope (T14) at Mauna Kea

·      Teide Observatory's Two-meter Twin Telescope

·      Weizmann Astrophysical Observatory (M01)

·      Very Large Telescope

·      Vera C Rubin Observatory in Chile

·      NASA Infrared Telescope Facility

·      Hubble Space Telescope

·      James Webb Space Telescope (JWST)

·      Gran Telescopio Canarias

·      1.2m infra-red telescope on Mount Abu, India

·      Space Missions and Spacecraft

·      Transiting Exoplanet Survey Satellite (TESS)

·      SPHEREx mission

·      ExoMars Trace Gas Orbiter (TGO)

·      Colour and Stereo Surface Imaging System (CaSSIS)

·      Mars Reconnaissance Orbiter

·      Tianwen-1 (China)

Research Institutions

·      Instituto de Astrofísica de Canarias (IAC)

·      Lowell Observatory

·      California Institute of Technology

·      Physical Research Laboratory, India

·      European Space Agency (ESA)

·      China National Space Administration (CNSA) 

Discoveries and Predictions 

Here is a summary of the major findings about the comet: 

The comet reached perihelion as predicted on October 29, 2025. Closest approaches to Venus, Mercury and Mars were as predicted (see table below), with the calculations becoming more precise as the dates approached ^[2]. 

Object	Date
Mars	2025-Oct-03 04:38 UT
Mercury	2025-Oct-08 02:43 UT
Venus	2025-Nov-03 05:56 UT
Jupiter (Expected)	2026-Mar-16 12:22 UT

The results now available point to a fascinating origin for the comet.

Yiyang Guo et al have looked at the possible gravitational perturbations which could have led to the orbital parameters and speed of 3I/ATLAS. After looking at 30 million stars in the Gaia catalogue, they have identified 25 which could have led to the orbital characteristics of 3I/ATLAS, and conclude that the comet originated in the thin disk of the Milky Way. 

Hopkins et al, on the other hand, have used the Ōtautahi–Oxford population model of interstellar objects, which takes into account not only the Gaia stars but also galactic dynamics and protoplanetary disk chemistry to deduce that the comet originated in the thick disk of the Milky Way. If it is indeed from the thick disk, 3I/ATLAS is probably more than 7 billion years old ^[3][4]. 

This is an illustration of how different “modes of attack” can yield different results on the same data. There will be consensus once there is more data, or when one methodology emerges superior to the other. 

Composition of 3I/ATLAS 

Observations of the coma of comet 3I/ATLAS show the presence of a higher concentration of carbon dioxide than in comets that originate within the Solar System (see graph below). The proportion of carbon monoxide is also high ^[5].

According to a paper submitted to the astrophysical journal, along with the high carbon dioxide and carbon monoxide concentrations, the spectroscopic data indicate “red spectral slopes” that show that the comet was irradiated by galactic cosmic rays. These rays irradiate CO₂ to CO, while synthesizing organic-rich crusts ^[6]. 

The proportion of methanol relative to hydrogen cyanide is among the highest ever recorded in any comet. This indicates that other protoplanetary disks (the disks of matter orbiting a star that later coalesce into planets, satellites, etc.,) can have very different compositions ^[7][8]. 

An interesting point here – the comet C/2016 R2, a long period comet that originated in the Solar System, also exhibits the high concentration of methanol relative to hydrogen cyanide and a high concentration of carbon dioxide. This does not reduce the significance of these discoveries, but contributes to strengthening some of the theories on the formation of comet C/2016 R2.

Also intriguing are traces of nickel vapor. Nickel is not a rare finding, but it is usually accompanied by iron ^[8]. 

As it approached the Sun, the sublimation of water in the nucleus led to jets and ice volcanoes on the surface, as submitted in a paper dated November 24, 2025 ^[4]. These cryovolcanoes might be the result of the metals corroding and acting as catalysts to start off energetic Fischer-Tropsch reactions ^[9]. 

[The Fischer–Tropsch process (FT) is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons. These reactions occur in the presence of metal catalysts, typically at temperatures of 150–300°C and pressures of one to several tens of atmospheres.] 

Are there more questions than answers? Certainly, yes. And there will be answers coming as the normal progress of scientific discovery unfolds. This is a quiet triumph of the scientific method. Scientific research is not a sprint but a marathon. It is to be expected that many more papers will be published this year, as the results are analysed and peer-reviewed.  Databases show promising numbers: Arxiv.org lists 78 articles on 3I/ATLAS that have been submitted or published, and Google Scholar, 518. 

The Predictions That Never Came True 

It’s now time to look back on the pseudoscience that heralded the visit of 3I/ATLAS. As we know, no spaceship came from behind the Sun to attack us as insinuated by some scaremongers. But what about the other claims? 

Let me now go back to table below, from the paper by Loeb et al. This paper was rehashed in a number of YouTube videos and articles. 

These are the reasons put forward for the theory that Comet 3I/ATLAS is of technological origin:

As stated in the previous article (see here), points 1 – 3 were already debunked at the time of writing. Let’s look at points 4 – 9 now: 

Quite obviously, there were no interceptions of planets, no solar sails and no spaceship attacking the Earth. There was no acceleration observed other than that expected through the natural processes of gravity and outgassing. 

Avi Loeb

Dr Loeb has now published yet another essay on the comet, where he paraphrases the actual scientific discoveries and conveniently leaves out all his failed predictions. He ends the essay with an ominous “Are we missing something” – a sentence which is the “most highlighted” according to the website. He has also been interviewed by Fox News – an over 20-minute interview where he essentially says nothing, but keeps repeating the word “anti-tail” 

His Harvard page reveals that Dr Loeb has written close to 60 articles on 3I/ATLAS. I’m listing some of them here to show how he merrily “moves the goalposts” even as his theories are discredited by science. 

His writings leading up to perihelion: 

"Is the Interstellar Object 3I/ATLAS Alien Technology?" (July 16, 2025)

"How to Distinguish a Population of Interstellar Rocks from a Fleet of Spacecraft?" (September 8, 2025)

"Was the Wow! Signal Emitted from 3I/ATLAS?" (September 28, 2025)

"The Acid Test of 3I/ATLAS at Perihelion" (October 28, 2025) 

After perihelion occurred as predicted, without any alien attack: 

"Afterthoughts on the Non-Gravitational Acceleration of 3I/ATLAS at Perihelion" (October 31, 2025) 

Starting off the next story… 

"Do the Anomalies of 3I/ATLAS Flag Alien Technology or an Unfamiliar Interstellar Iceberg?" (November 17, 2025)

"3I/ATLAS is Hiding Behind a Veil of Dust" (December 27, 2025)

"If 3I/ATLAS is a Comet, Why Would the CIA Neither Deny, Nor Confirm the Existence of Records on It?" (January 5, 2026) 

The frightening part

Comet 3I/ATLAS is only the third known interstellar object, but there is plenty of reason to expect more in the future. Is every interstellar spacecraft, or indeed every breakthrough discovery in science going to be met with speculation and pseudoscience, not curiosity and wonder? 

This is the Google Trends graph for interest in Comet 3I/ATLAS:

As you can see, the interest peaked with the conspiracy theories, and died down when the pseudoscience failed. 

The people who produced these articles and videos have not been taken to task by anyone. Apparently, the public are happy to read pseudoscience, believe it, and when it fails, to move on. Pseudoscientists also have the luxury of keeping their output “current” – one of Loeb’s essays was a response to a celebrity posting something on social media! 

Why is Avi Loeb allowed to keep moving the goalposts – to keep changing his narrative when there is a system to keep scientists accountable? 

This exemplifies the quote at the beginning of this article - “A lie can travel halfway around the world before the truth puts on its shoes.” 

References:

1. Prasad, S. N. “Interstellar Visitor 3I/ATLAS – Alien Technology? Is It Just Much Ado About Nothing?”
2. “3I/ATLAS.” Wikipedia: The Free Encyclopedia, 2 Feb. 2026, en.wikipedia.org/wiki/3I/ATLAS. Accessed 2 Feb. 2026.
3. JWST Detection of a Carbon Dioxide Dominated Gas Coma Surrounding Interstellar Object 3I/ATLAS. Zenodo, zenodo.org/records/16941949. Accessed 2 Feb. 2026.
4. Trigo-Rodríguez, Josep M., et al. “Spectrophotometric Evidence for a Metal-Bearing, Carbonaceous, and Pristine Interstellar Comet 3I/ATLAS.” arXiv, 24 Nov. 2025, arxiv.org/abs/2511.19112. Accessed 2 Feb. 2026.

5.     Álvarez-Candal, A., et al. “X-SHOOTER Spectrum of Comet 3I/ATLAS: Insights into a Distant Interstellar Visitor.” Astronomy & Astrophysics, vol. 700, 2025, aanda.org/articles/aa/full_html/2025/08/aa56338-25/aa56338-25.html. Accessed 2 Feb. 2026.

6.     Guo, Yiyang, Luyao Zhang, Fabo Feng, Zhao-Yu Li, Anton Pomazan, and Xiaohu Yang. “Search for Past Stellar Encounters and the Origin of 3I/ATLAS.” The Astronomical Journal, vol. 170, no. 6, 2025, article 362, doi:10.3847/1538-3881/ae1833. Accessed 2 Feb. 2026.

7.     Loeb, Abraham, Adam Hibberd, and Adam Crowl. Is the Interstellar Object 3I/ATLAS Alien Technology? Harvard-Smithsonian Center for Astrophysics, lweb.cfa.harvard.edu/~loeb/HCL25.pdf. Accessed 2 Feb. 2026.

8.  Loeb, Avi. “The Massive Nucleus of 3I/ATLAS and Its Puzzling Methane Outgassing, Based on  New Data From the Hubble and Webb Telescopes.” Medium, 2026, avi-loeb.medium.com/the- massive-nucleus-of-3i-atlas-and-its-puzzling-methane-outgassing-based-on-new-data-from-the-72e540d8fe46. Accessed 2 Feb. 2026.
9.  ChicagoLIVE. “Avi Loeb: CIA Would Neither Confirm nor Deny Records on 3I/ATLAS …”  YouTube, 2025, www.youtube.com/watch?v=KOt6R8-i30U. Accessed 2 Feb. 2026.