No, Aliens Aren’t “Revving” 3I/ATLAS — The Blue Glow Has a Simpler Story

Short answer: There’s no evidence aliens are steering 3I/ATLAS. The “blue” flash and tiny extra push it showed near the Sun both match what a natural comet can do. But the true story is still fascinating — and stranger than the headline suggests.

Let’s start with the biggest twist: the comet really did turn bluer than the Sun for a brief moment near its closest pass to the Sun. Instruments saw a rapid brightening and a distinctly blue tint on October 29, 2025 — exactly the kind of signature you’d expect from gas emissions like ionized carbon monoxide, not from a sci‑fi engine.

The Big Corrections

• 3I/ATLAS is real and interstellar. It’s the third confirmed interstellar object, discovered July 1, 2025 by the ATLAS survey and designated C/2025 N1 (ATLAS). “3I” means “third interstellar.” Source: Minor Planet Center notice (MPEC) minorplanetcenter.org

• Closest approach to Earth: December 19, 2025, at about 1.8 AU (roughly 167 million miles). Source: TheSkyLive ephemeris

• The “blue” report is real — and natural. Spacecraft photometry (SOHO/LASCO, STEREO, GOES‑19) documented the blue tint during a near‑Sun brightening; researchers note it’s consistent with gas like CO/CO+. Source: preprint on the photometry arXiv

• No, it doesn’t “leave the solar system in January.” After December’s Earth flyby, 3I/ATLAS keeps moving through the inner solar system, passing Jupiter on March 16, 2026, before heading outward on a hyperbolic path. January 2026 is far too soon to declare it “gone.” Source: The Planetary Society explainer planetary.org

Where the Alien Engine Idea Came From — and What It Missed

Harvard astrophysicist Avi Loeb did write that a tiny “non‑gravitational acceleration” measured around perihelion could be a technosignature — “the technological signature of an internal engine” — and floated possibilities like a hot engine or artificial light. He also clearly offered a natural explanation: ionized carbon monoxide, a classic comet gas. Source: Loeb’s Oct 31, 2025 Medium post avi-loeb.medium.com

What the original article did was turn that speculation into a claim. It also embellished a quote: the “lose 10–20% of its mass” wording and “moved it away from its original trajectory” phrasing do not appear in Loeb’s post. What he actually inferred was more conditional — that if the measured push came from a rocket‑like effect, you’d expect about a tenth of the mass lost over a month and roughly half over six months. That’s a thought experiment, not a measurement.

Meanwhile, mainstream researchers — and the instruments — point to a natural comet:

• Early observations showed a coma and tail and detected volatile gases consistent with an ordinary (if interstellar) comet: a CO2‑dominated coma with H2O, CO, and more. Source: Hubble/JWST follow‑up arXiv

• Coverage by major outlets and scientists reflects the consensus: 3I/ATLAS is almost certainly a natural interstellar comet. Source: The Guardian overview theguardian.com

So What Was That “Non‑Gravitational Acceleration”?

Think of a comet as a dirty snowball with tiny thrusters hidden inside — not machines, but jets of gas and dust. As sunlight heats its surface, trapped ices vaporize and escape. The outflow acts like a spray can pushing back on your hand: a small but measurable “rocket effect.” Astronomers call these deviations from pure gravity “non‑gravitational accelerations,” and they are common in comets.

3I/ATLAS showed a small extra push near the Sun. Paired with the blue color spike, the simplest reading is outgassing — especially CO/CO+, which glows blue and escapes rapidly when heated. That’s exactly what the spacecraft photometry flagged.

How the Blue Glow Fits the Physics

• Near perihelion (Oct 29, 2025), 3I/ATLAS brightened and turned bluer than the Sun.
• Blue color in comets often comes from gas emissions, especially ionized carbon monoxide (CO+), rather than dust. Dust usually reddens light.
• A brief, intense gas release can both change the color and give the comet a tiny shove — no alien engine required.

Source: photometry analysis arXiv

What We Verified — And What’s Still Uncertain

Verified

• Interstellar status and naming (“3I”). MPC
• Dec 19, 2025 closest approach at ~167 million miles. TheSkyLive
• Blue perihelion event consistent with gas emission. arXiv photometry
• Natural‑comet composition detected (CO2, H2O, CO). arXiv spectroscopy
• Not leaving the solar system in January; Jupiter pass in March 2026. The Planetary Society

Uncertain or needs more data

• The exact breakdown of gases during the blue flare (how much CO vs. other species).
• The detailed shape/rotation of the nucleus, which affects how jets point and how strong the “rocket effect” becomes.
• Whether tiny fragments or dust outbursts contributed to the observed brightening.

Our Reporting Process

• We checked the discovery, designation, and orbit with the Minor Planet Center and ephemeris tools.
• We read the spacecraft photometry paper documenting the blue event and its natural explanation.
• We reviewed Avi Loeb’s Medium post to quote it accurately and to preserve his stated natural alternative.
• We consulted a general explainer on 3I/ATLAS’s trajectory and timeline to correct the “January exit” error.

Links to all sources are included above for you to read in full.

Why This Matters

The temptation to frame every interstellar visitor as an alien probe is understandable — especially after the oddities of ‘Oumuamua. But when a world‑class set of instruments sees blue gas emissions and a gentle push that comets commonly show, the burden of proof sits squarely on anyone claiming an engine. Right now, the evidence points to 3I/ATLAS being a natural comet doing spectacularly comet‑like things.

The Bottom Line

• No verified alien engine. The “engine” idea is speculative; the data fit a natural comet.
• The blue glow has a textbook explanation. Ionized CO/CO+ is the prime suspect.
• Mark your calendar: closest to Earth on Dec 19, 2025 — still a safe 167 million miles away.
• No January goodbye. 3I/ATLAS will still be in the solar system well into 2026.

If you’d like, I can pull the latest JPL Horizons ephemerides for Dec 19 or roundup new spectroscopy to track how the “blue” signal evolved after perihelion.