Harvard Astrophysicist Avi Loeb Says Interstellar Object 3I/ATLAS Now Shows Non-Gravitational Acceleration
“Complacency with traditional ideas is the enemy of scientific curiosity.” — Avi Loeb
A New Mystery From Deep Space
This week, scientists confirmed that the newly discovered interstellar object 3I/ATLAS, the third known visitor from beyond our solar system, is displaying non-gravitational acceleration, meaning its movement cannot be explained by gravity alone. The revelation has reignited debate over whether the object could be a natural comet or something more unusual, possibly even alien technology.
Harvard astrophysicist Avi Loeb, who leads the Galileo Project for the search for extraterrestrial artifacts, discussed the object in a feature published this morning by The Times of London, followed by several interviews that quickly went viral across scientific and investor circles.
A New Kind of Comet or Something Else Entirely
3I/ATLAS was first detected earlier this year moving on a hyperbolic trajectory, indicating it originated outside our solar system. Its path and velocity have puzzled astronomers. According to new data, its acceleration cannot be fully attributed to the Sun’s gravity echoing anomalies seen with ʻOumuamua, the first known interstellar object discovered in 2017.
Loeb points out that 3I/ATLAS shows no visible cometary tail, a tell-tale sign of gas or dust outgassing, yet still appears to be picking up speed as it nears the inner solar system. “As of now, the glow of light ahead of 3I/ATLAS can be maintained for six months by the ablation of a millimeter-thick layer of dirt on the surface of a 20-kilometer object,” Loeb wrote. That makes it both unusual and potentially significant.
Loeb: “Science Must Stay Open-Minded”
In his latest public statements, Loeb emphasized that the object is most likely natural, but warned against dismissing unconventional possibilities too quickly. He told The Times:
“I would be relieved to know that it’s an icy rock, because in that case humanity will not face any risk.”
Yet, he added that keeping an open mind is essential to discovery:
“If archaeologists assumed they’d only ever find rocks, they’d never have discovered ancient artifacts. The same applies to the cosmos.”
The Case for Studying 3I/ATLAS
Loeb argues that investigating such anomalies isn’t just about curiosity, it’s about security and opportunity. He has urged governments and investors to support research into interstellar objects, suggesting that the discovery of alien technology could yield profound technological and economic benefits.
During a recent Q&A with high-net-worth investors, Loeb outlined a potential “alert system” of solar-orbiting telescopes and interceptors to study future interstellar visitors before they leave the solar system. He contends that understanding these objects could one day protect Earth from extraterrestrial threats or open doors to technologies far beyond our current capabilities.
From Harvard to the Heavens
Loeb’s Galileo Project, based at Harvard’s Center for Astrophysics, is now expanding, hiring new postdoctoral researchers to analyze incoming data on 3I/ATLAS and future interstellar visitors expected to be detected by the NSF-DOE Rubin Observatory in Chile. The observatory is projected to find dozens of such objects in the next decade. Loeb has even developed a “Loeb Scale” for assessing the technological threat level of interstellar objects. On that scale of 0 to 10, he ranks 3I/ATLAS at 4 not alarming, but worthy of close scrutiny.
“Having a 40 percent chance of an accident while crossing the street argues in favor of keeping our eyes open,” he said.
The Stakes: Curiosity or Complacency
Loeb’s broader message cuts through the noise: if humanity refuses to investigate anomalies like 3I/ATLAS, we risk missing transformational discoveries.
“A lack of curiosity about interstellar objects keeps us ignorant—like cows grazing in a field, unaware of satellites flying above their heads.”
For Loeb, whether 3I/ATLAS turns out to be an alien craft or a cosmic snowball, the lesson is the same: scientific humility must replace dogma. As the object races toward the inner solar system, telescopes worldwide are tracking its acceleration. In the coming months, astronomers will determine whether 3I/ATLAS is a comet, an asteroid or something unprecedented in human history.
Sources
Loeb, A. “Should We Be Happier If 3I/ATLAS Is a Comet?” (Medium) — overview of his open-minded stance. https://avi-loeb.medium.com/should-we-be-happier-if-3i-atlas-is-a-comet-91b3f8e74f98 (Medium)
- Loeb, A. “Testing the Nature of 3I/ATLAS by Its Non-Gravitational Acceleration.” (Medium) — technical note on non-gravitational acceleration. https://avi-loeb.medium.com/testing-the-nature-of-3i-atlas-by-its-non-gravitational-acceleration-4089015ceaee (Medium)
- Loeb, A. “Is the Interstellar Object 3I/ATLAS Alien Technology?” (Medium) — explores possibility of extraterrestrial origin. https://avi-loeb.medium.com/is-the-interstellar-object-3i-atlas-alien-technology-b59ccc17b2e3 (Medium)
- NASA Science: “Comet 3I/ATLAS” — official NASA summary of the object. https://science.nasa.gov/solar-system/comets/3i-atlas/ (NASA Science)
- Scientific American: “New Interstellar Object 3I/ATLAS’s Biggest Mysteries Explained.” https://www.scientificamerican.com/article/new-interstellar-object-3i-atlass-biggest-mysteries-explained/ (Scientific American)
- arXiv preprint: “Upper Limit on the Non-Gravitational Acceleration and Lower Limits on the Nucleus Mass and Diameter of 3I/ATLAS.” https://arxiv.org/abs/2509.21408 (arXiv)
Additional Reading / Context
- Livescience article on the controversial hypothesis: https://www.livescience.com/space/extraterrestrial-life/here-we-go-again-controversial-paper-questions-whether-interstellar-visitor-3i-atlas-is-possibly-hostile-alien-tech-in-disguise (Live Science)
Wired piece: “Everything We Know About the Third Interstellar Object in History” https://www.wired.com/story/heres-what-we-know-about-the-third-interstellar-object-in-history/ (wired.com
