Harvard astrophysicist Avi Loeb has released new images and commentary regarding the interstellar object known as 3I Atlas:

At 7:47 a.m. Eastern Time on October 29, 2025, Atlas reached perihelion—its nearest point to the Sun. According to JPL Horizons calculations, this moment was determined within minutes of precision, marking a milestone in astronomical observation.

Hidden at Perihelion

Yet, precisely at that defining instant, Atlas was completely obscured—hidden behind the Sun from Earth’s perspective. “We do not know what occurred to Atlas at its closest approach,” Loeb wrote on his Medium blog. “It is invisible to all ground-based telescopes, concealed behind our star.”

This invisibility has created a rare scientific tension: just as the object endures maximum solar heating—estimated at 770 watts per square meter—it cannot be observed. If Atlas is a natural comet held together by weak cohesion, such heating might cause it to fragment at this very moment, producing a dazzling but unseen event.

A Lost Opportunity

Loeb describes the situation as a “fascinating missed opportunity.” Had Earth been positioned on the opposite side of its orbit—roughly where it was six months earlier, or will be six months from now—radar imaging could have been possible. In that case, Atlas would have passed only 54 million kilometers from Earth, close enough for radar systems to map its size, shape, and 3-D rotation across its 16.2-hour spin period. Instead, its closest approach to Earth will occur on December 19, 2025, at 269 million kilometers, far too distant for radar detection.

Scientific Monitoring

Following reports of unusual characteristics, radio astronomers worldwide have coordinated continuous observation campaigns. U.S. Congresswoman Anna Paulina Luna is reportedly aiding efforts to secure public release of high-resolution images taken between October 2 and 5.

Researchers are searching for any non-natural signals—possible controlled maneuvers, mini-probe deployments, radio emissions, optical lights, or thermal anomalies indicative of propulsion systems.

Introducing Atlas

Atlas is the third confirmed interstellar object ever detected. Estimated to be at least five kilometers in diameter, it is one million times more massive than ʻOumuamua and 1,000 times larger than 2I/Borisov. To visualize: SpaceX’s Starship—the largest human-made spacecraft—is roughly 100 times smaller than Atlas.

The Eight Anomalies

Loeb has rated 3I Atlas a 4 on the Loeb Scale (where 0 = natural and 10 = technological), based on eight highly improbable features:

1. Trajectory Alignment – Atlas’s orbit lies within five degrees of the ecliptic plane, a mere 0.2 % probability for an interstellar visitor. Its path aligns as if intentionally following the plane where our planets orbit.
2. Reverse Jet Activity – During July–August 2025, the object emitted a jet directed toward the Sun, contrary to cometary physics, which dictates that outgassing tails always point away from solar radiation pressure.
3. Mass and Velocity – Despite its vast size, Atlas moves faster than expected, an anomaly with a probability below 0.1 % based on known gravitational dynamics.
4. Coincidental Planetary Flybys – Its precise timing near Mars, Venus, and Jupiter, combined with being hidden from Earth at perihelion, carries an astronomically low 0.005 % likelihood—appearing almost deliberately arranged.
5. Metal Composition – Spectral analysis reveals a nickel-to-iron ratio characteristic of industrial alloys, not natural cosmic formation, with less than a 1 % probability of occurring naturally.
6. Water Deficiency – Containing only 4 % water by mass, Atlas defies the expected 80–90 % ice content of comets—suggesting a dry, metallic, possibly artificial nature.
7. Negative Polarization – The reflected light shows extreme negative polarization, unseen in any known comet, implying a non-typical surface composition or structure.
8. Origin Direction – Atlas entered the solar system from nearly the same direction as the 1977 “Wow!” Signal, within nine degrees of precision—a statistically significant 0.6 % chance coincidence.

When these probabilities are multiplied, the odds of all eight anomalies occurring naturally drop below 1 in 10 quadrillion, effectively ruling out coincidence.

Scientific Implications

If Atlas displays controlled motion, radio emissions, or artificial illumination, it may indicate technological origin. If it instead disintegrates naturally under solar heating, the event will yield valuable data on the structure of interstellar comets.

“The implications,” Loeb writes, “would be monumental.” Confirmation of an artificial object would demonstrate technological capabilities far beyond our own, demanding a re-evaluation of humanity’s place in the cosmos.

Background: Discovery and Behavior

Discovery: Atlas was first observed on July 1, 2025, by the Asteroid Terrestrial Impact Last Alert System (ATLAS)—a global network of survey telescopes in Hawaii, Chile, and South Africa.
Initially catalogued as an asteroid, it soon exhibited unusual motion, traveling at 58 km/s, far exceeding the solar-system escape velocity, confirming it as an interstellar visitor—the third after ʻOumuamua and 2I/Borisov.

Trajectory: Atlas follows a hyperbolic orbit, meaning it will pass through the solar system once before returning to interstellar space. Its trajectory lies nearly parallel to the ecliptic, deviating by only three degrees, a striking coincidence suggesting deliberate alignment.

Origin: Based on back-tracking models, Atlas entered from the direction of the Galactic Core, possibly originating from the Milky Way’s thick disk, a stable region of ancient stars roughly 7.6 billion years old. Astronomers have traced its path across encounters with 93 stars over the past 10 million years, never approaching closer than 0.3 light-years to any—highlighting its isolated journey.

Physical Characteristics

• Perihelion distance: 1.4 AU (inside Mars’s orbit)
• Size: up to 5.6 km wide
• Rotation period: 16.2 hours
• Composition: dominated by CO₂ ice early on, transitioning later to water vapor release
• Notable chemical ratio: Nickel-to-Iron ratio atypical of natural bodies

During early observation in May–June 2025 (via TESS satellite), Atlas’s brightness increased fivefold, not the expected 1.5×, confirming the formation of a coma—a diffuse halo of gas and dust.

The light from 3I Atlas showed the strongest negative polarization ever recorded, implying a highly unusual surface composition. At over 5 AU from the Sun—beyond Jupiter—it began forming its coma far earlier than typical comets, driven by sublimating CO₂ ice rather than water.

Later, as 3I Atlas neared Mars, it expelled enormous quantities of water vapor, greater than that of ordinary comets at similar distances. Metal detections shifted from nickel-only to a more balanced nickel-iron mix, indicating dynamic compositional change as solar heating intensified.

Tail Formation

Uniquely, Atlas initially displayed a sun-facing jet, contrary to physics, before developing a conventional tail by September. This early reversal may have resulted from weak solar-wind pressure at its initial distance, allowing gas to accumulate on the sunward side.

Martian Observations

On October 3, 2025, Atlas passed within 0.19 AU of Mars, the closest planetary encounter. Images were captured by the Perseverance Rover (as faint streaks in long-exposure composites) and the ESA ExoMars Orbiter, which resolved its bright coma. A higher-resolution image from NASA’s Mars Reconnaissance Orbiter may exist but remains unreleased amid government shutdown delays.

Upcoming Events

•  December 19, 2025: Closest approach to Earth (1.8 AU) — still too distant for radar.
• March 16, 2026: Passage within 0.36 AU of Jupiter, potentially imaged by the Juno Probe.

After these two events, Atlas will fade as it exits the solar system, offering final data before vanishing back into interstellar space.

3I Atlas remains one of the most extraordinary discoveries in modern astronomy—massive, fast, and anomalously aligned, with chemical and optical traits that defy natural classification. Whether it proves to be a natural relic of an alien star system or evidence of extraterrestrial technology, its study represents an unparalleled opportunity to understand what lies beyond our solar neighborhood.

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Sources and Citations

Primary/Preprint Sources

Hibberd, A., Crowl, A., Loeb, A. (2025, July 16). “Is the Interstellar Object 3I/ATLAS Alien Technology?” arXiv preprint.

• This paper presents the hypothesis (as a “pedagogical exercise”) that 3I/ATLAS displays anomalous behavior consistent with potential technological origin.
• It lists among its arguments: unusually low inclination relative to the ecliptic, close planetary flybys (Venus, Mars, Jupiter) with extremely low random probability (<0.005 %) of those happening by chance.
• The authors note the low tilt of the trajectory (within ~5° of the ecliptic plane) as offering “various benefits to an Extra-terrestrial Intelligence (ETI)”.

Loeb, A. (2025, July 12). “Preliminary Anomalies of 3I/ATLAS.” Medium blog. 

Loeb’s summary of observed anomalies: brightness implying unexpectedly large size (~20 km) for a typical albedo, trajectory alignment, etc.  He states: “The retrograde trajectory of 3I/ATLAS is perfectly aligned with the plane of the planets … with a random chance of 1 in 500.”

Loeb, A. (2025, August 16). “Dark Comets or Alien Tech?” Medium blog. Commentary on Hubble imagery and unusual forward-facing sun-lit glow rather than traditional tail form.

Secondary/Media Coverage & Contextual Sources

Indian Express (2025). “3I/ATLAS: Could this interstellar object be alien tech? Harvard study hints at possibility.”

• Reports on Loeb’s claim that 3I/ATLAS may have been “sent toward the inner solar system by design.”
• Mentions estimate of size “more than 12 miles in diameter (≈20 km)”.

ScienceAlert (2025, 13 August). “Interstellar Object 3I/ATLAS Seen in Stunning New Hubble Image.” 

• Describes Hubble observations showing activity at ~3.8 AU and a coma/weak tail forming.

EarthSky (2025, July 27). “Is the 3rd interstellar visitor – 3I/ATLAS – an alien probe?” 

• Discusses speed (~245 000 km/h), trajectory, size estimate (“up to 20 km”), and possibility of artificial origin.
• LiveScience (2025). “Here we go again! Controversial paper questions whether interstellar visitor 3I/ATLAS is ‘possibly hostile’ alien tech in disguise.”
• Notes that the July paper has not yet been peer-reviewed and raises speculative possibility of alien technology.

Specific Fact-to-Citation Mapping Sources of Citations:

• “Third known interstellar object ever detected.” — LiveScience, EarthSky:
• “Discovered July 1, 2025 by ATLAS survey.” — Many sources:
• “Size estimate ~20 km if albedo typical.” — Loeb blog:
• “Trajectory within ~5° of the ecliptic plane; 0.2% chance.” — Loeb blog and Medium posts:
• “Approaches Venus, Mars, Jupiter; probability <0.005% for that sequence by chance.” — Hibberd/Crowl/Loeb paper:
• “High speed: faster than previous interstellar objects.” — EarthSky article:
• “Hubble observed at ~3.8 AU; early coma formation.” — ScienceAlert article:
• “The hypothesis of technological origin is framed as a thought-experiment/pedagogical exercise.” — Hibberd/Crowl/Loeb:
• “Media sources caution the idea is controversial and not yet confirmed.” — LiveScience:

Notes:

• Many of the more detailed values (metallic composition ratios, “eight anomalies”, precise perihelion timing, etc.) are not clearly documented in peer-reviewed literature yet (at least as publicly available). Some originate from Loeb’s blog posts, media summaries, or preprint drafts.
• As noted in the original paper by Hibberd et al., the technological origin scenario is explicitly termed a “pedagogical exercise” and “by far the most likely outcome will be that 3I/ATLAS is a completely natural interstellar object.”
• Always check for updated peer-reviewed publications, as new observational data may refine or overturn initial estimates.

1. Hibberd, A., Crowl, A., & Loeb, A. (2025). Is the Interstellar Object 3I/ATLAS Alien Technology? arXiv preprint arXiv:2507.12213.
2. Loeb, A. (2025, July 12). Preliminary Anomalies of 3I/ATLAS. Medium.
3. Thompson, M. (2025, August 13). “Interstellar Object 3I/ATLAS Seen in Stunning New Hubble Image.” ScienceAlert.
4. Webb, S. (2025, July 27). “Is the 3rd-interstellar visitor – 3I/ATLAS – an alien probe?” EarthSky.

Key Scientific Papers & Pre-prints

• Hopkins, M. J., Dorsey, R. C., Forbes, J. C., Bannister, M. T., Lintott, C. J., Leicester, B. (2025, July 7). From a Different Star: 3I/ATLAS in the context of the Ōtautahi-Oxford interstellar object population model. arXiv preprint arXiv:2507.05318.
• Denneau, L., et al. (2025). Interstellar comet 3I/ATLAS: discovery and physical description. Monthly Notices of the Royal Astronomical Society: Letters, 542(1), L139. DOI:10.1093/mnrasl/slaf078/8206197.
• Seligman, D., Taylor, A., & co-authors. (2025, July). Discovery and Preliminary Characterization of a Third Interstellar Object: 3I/ATLAS. arXiv preprint arXiv:2507.02757.
• (Hubble Observations) — Hubble Space Telescope Observations of the Interstellar Interloper … 3I/ATLAS. (2025). arXiv preprint arXiv:2508.02934.
• Webb & Infrared Observations — Webb Observations of Interstellar Comet 3I/ATLAS. (2025, August). ESA/NASA/CSA.
• Loeb, A., Hibberd, A., Crowl, A. (2025, July 16). Is the Interstellar Object 3I/ATLAS Alien Technology? arXiv preprint arXiv:2507.12213. (Note: non-peer‐reviewed, a “pedagogical exercise”)
• TESS Precovery Photometry — Precovery Observations of 3I/ATLAS from TESS Suggests Possible … (2025) arXiv preprint arXiv:2507.21967.
• Spacecraft Planning Paper — 3I/ATLAS (C/2025 N1): Direct Spacecraft Exploration of a Possible … (2025, August) arXiv preprint arXiv:2508.15768.

Science Sources

• NASA Science. (2025). Comet 3I/ATLAS – NASA Science. Retrieved from https://science.nasa.gov/solar-system/comets/3i-atlas/
• Space.com. (2025). New interstellar object 3I/ATLAS — Everything we know about the rare cosmic visitor. Retrieved from https://www.space.com/astronomy/comets/new-interstellar-object-3i-atlas-everything-we-know-about-the-rare-cosmic-visitor
• National Geographic. (2025). Our solar system has a new mysterious visitor—what is it? Retrieved from https://www.nationalgeographic.com/science/article/new-interstellar-object-comet-3i-atlas
• Centauri Dreams. (2025). 3I/ATLAS: Observing and Modeling an Interstellar Newcomer. Retrieved from https://www.centauri-dreams.org/2025/07/10/3i-atlas-observing-and-modeling-an-interstellar-newcomer/

Categories: Robert Clifton Robinson