By Ziggy, Face the Strange

When Avi Loeb writes about interstellar visitors, the world listens. Sometimes because the data are genuinely baffling, sometimes because he dares to ask questions others would sidestep, and sometimes because the word alien slips in before the ink dries.

With 3I/ATLAS, the third confirmed interstellar object after `Oumuamua (2017, Pan-STARRS survey) and Borisov (2019, Crimean Astrophysical Observatory), we’ve been able to watch Loeb’s thinking evolve in real time: from cautious enthusiasm, to bold speculation, to a more measured engagement with the data. It’s not easy to keep up - he’s publishing now daily and sometimes multiple times a day!

The pessimist would say he’s using the strangeness of 3I/ATLAS to grow his audience. The optimist would say 3I/ATLAS is wonderfully strange and is worth the attention.

That evolution isn’t just about Loeb. It’s a glimpse into how science itself wrestles with the unknown: the numbers first, the anomalies next, and the models that follow.

Loeb’s early commentary highlighted how faint objects like this usually slip past us. With an estimated absolute magnitude pointing to a nucleus only a few hundred meters across, it sat between Borisov (a clear comet) and `Oumuamua (an enigmatic rock with no coma). In this phase, Loeb was more teacher than provocateur: explaining orbital mechanics, albedo assumptions, and the rarity of such detections given survey limits.

By mid-July, the tone shifted. The numbers were what caught Loeb's attention. In a detailed analysis, he calculated that 3I/ATLAS's retrograde trajectory being aligned so closely with the ecliptic plane had only a 0.2% probability of occurring by chance.

More striking still, its arrival timing was fine-tuned to pass unusually close to not just Jupiter (54 million km in March 2026), but also Mars and Venus representing a convergence with a probability of just 0.005%.

For an object potentially 20 kilometers wide, such deliveries from interstellar space should occur only once every 10,000 years, yet here was 3I/ATLAS arriving within a decade of our first two confirmed interstellar visitors.

To Loeb, these weren't just curiosities, they were statistical red flags demanding explanation. Was this coincidence, selection bias in our detection methods, or something more deliberate?

Then came the Hubble Space Telescope (HST) observations. A diffuse coma appeared ahead of the nucleus, yet spectroscopy from ground-based instruments like the VLT (Very Large Telescope) revealed no clear traces of H₂O, CO, or CO₂ — the usual culprits in cometary outgassing. A dust coma without volatiles is a paradox: what mechanism drives it?

This is where Loeb leaned into the provocative. One article cast 3I/ATLAS as a potential “cosmic Turing Test,” engineered to test whether we’d notice. Another suggested technology couldn’t be ruled out. To many scientists, that was premature. But Loeb’s stance was consistent: anomalies are worth more than a shrug.

By August, Loeb pivoted again: this time toward modeling. Using Hubble’s brightness data, he showed how micron-sized dust grains (1–10 μm) moving at tens of meters per second could explain the glow via forward scattering. No exotic propulsion, just physics.

He also noted spectroscopic quirks: nickel emission lines without corresponding iron lines. Was this unusual mineralogy, instrument sensitivity, or something else? Loeb flagged it but resisted overreaching. He pointed ahead to missions like SPHEREx (Spectro-Photometer for the History of the Universe, Epoch of Reionization, and Ices Explorer), which could eventually constrain surface composition more tightly.

And then came the now-famous Loeb Scale, a 0–10 index for ranking interstellar objects on their likelihood of being natural versus artificial. Borisov sits at 0. `Oumuamua lands somewhere around 3–4. 3I/ATLAS? Loeb left it open, but given what we know, I’d put it at 2.5 at most. Odd, yes. Artificial, highly unlikely.