“We Need to Be Curious”: Avi Loeb on 3I/ATLAS and the Limits of Science
Image: NASA, ESA, David Jewitt (UCLA); Image Processing: Joseph DePasquale (STScI)
Written by Christopher Sharp - 6 November 2025
The object designated 3I/ATLAS has sparked significant media attention.
This interstellar visitor, arriving from beyond our Solar System, exhibits unusual characteristics that set it apart from any comet previously observed.
Since its official discovery in July 2025 by the Asteroid Terrestrial-impact Last Alert System (ATLAS) telescope at Río Hurtado, Chile, the object has sparked lively debate within the scientific community.
Science communicator Brian Cox was unequivocal: ‘Comet 3I/ATLAS is a comet … entirely natural in origin,’ he wrote, emphasising that its behaviour matches what we expect from icy visitors.
Meanwhile, another science communicator, Neil deGrasse Tyson, has also weighed in, urging caution about alien-craft speculation and focusing instead on the observable evidence.
While many astronomers agree the body behaves like a natural comet, the discussion remains open - and that’s exactly where the media spotlight falls.
Harvard astrophysicist Avi Loeb isn’t so certain it is a comet - at least in the normal sense, though.
“I'm attending to the evidence. And you know, if it shows anomalies, we have to explain them,” he told Liberation Times.
Writing on his Medium blog, Loeb outlines a striking list of anomalies, including:
An uncanny orbit: 3I/ATLAS travels backwards (retrograde) but still hugs the same plane as the planets — within just five degrees — something Loeb says has only a 0.2 % chance of happening by coincidence.
A jet that points the wrong way: In July and August 2025, it blew a jet toward the Sun rather than away from it — an “anti-tail” that can’t be explained by perspective alone.
Too big, too fast: Its core could be a million times heavier than the first interstellar object, ʻOumuamua, and a thousand times heavier than the second, 2I/Borisov — yet it’s moving even faster.
Perfect cosmic timing: Its flight path brought it unusually close to Mars, Venus, and Jupiter, while its closest pass to the Sun occurred when it couldn’t be seen from Earth — odds Loeb puts at 0.005 %.
Industrial-grade metals: The gas around it contains far more nickel than iron — a ratio similar to man-made alloys and unlike any comet ever studied.
Almost no water: Only around 4 % of its mass appears to be water, even though water ice is normally the main ingredient of comets.
Light that defies physics: It polarises light in the opposite way to every other known comet — a property never seen before.
A familiar direction: It entered the Solar System from nearly the same spot in the sky as the 1977 “Wow!” radio signal — within about nine degrees.
Bluer and brighter than the Sun: As it neared the Sun, it brightened faster than any other comet on record and shone with a bluish hue instead of the usual dusty glow.
A push with no exhaust: It’s accelerating as if something were propelling it — equivalent to losing more than ten per cent of its mass — yet no visible tail or debris explains it.
Above: Avi Loeb
Responding to those who insist 3I/ATLAS is nothing more than a natural comet, Loeb urges his peers to approach it with greater curiosity. As he puts it:
“We need to be curious, instead of comet experts who, from the start, argue that it’s just a regular comet.
“They said it’s water-rich — and then, when water was not found, they said, ‘Oh no, okay, so it’s CO₂-rich.’ When it moves in the same plane as the planets around the Sun, they say, ‘Well, it’s just a rare coincidence.’
“And when it turns out to have a mass a million times greater than the first interstellar object, ʻOumuamua, they say, ‘Well, strange things happen.’”
The dogmatic approach of some modern scientists toward 3I/ATLAS evokes an earlier age, when the Church and its astronomers clung to rigid models of the cosmos.
For centuries, Aristotle’s geocentric universe held sway over Christian cosmology: the Earth was at the centre, while the Sun, Moon, planets, and stars revolved around it.
But in the early 1600s, careful observation began to tell a different story.
Using a telescope, Galileo Galilei confirmed that Venus displayed a full set of phases — proof that it orbited the Sun, not the Earth.
This discovery struck at the very heart of the Aristotelian-Ptolemaic model that the Catholic Church had long embraced.
Unable to accept the implications, many astronomers attempted to preserve their worldview by inventing ever-more elaborate hybrid models — claiming that while the planets circled the Sun, the Sun itself still revolved around the Earth.
It was an effort to protect orthodoxy rather than to follow the evidence. And it ultimately failed, as the Church faced reality.
Loeb uses history to illustrate a simple truth — that the universe is indifferent to human dogma.
Finding the similarities amusing, Loeb quipped:
“To recognise this in context is to remember that the Earth was moving around the Sun 4.5 billion times before the Vatican even existed.
“So think about it — the Earth moving 4.5 billion times, again, again, again and again, 4.5 billion times. Then the Vatican comes along and says, ‘No, the Sun moves around the Earth.’
“Who cares? The Earth continued to move around.”
Above: Vatican City
Loeb’s curiosity about 3I/ATLAS is not without reason. New observations indicate the object has deviated from the trajectory expected under pure gravitational influence.
“There are new images today of 3I/ATLAS, and I calculated — based on the reported non-gravitational acceleration — that it did exhibit some deviation from the trajectory expected by gravity,” he said.
NASA’s Jet Propulsion Laboratory, which tracks the object’s motion, reported the values used in Loeb’s calculations.
“NASA’s Jet Propulsion Laboratory has a website where they monitor the motion of the object, and they provide the value for this non-gravitational acceleration. I calculated that it should have lost at least 13 % of its mass, given the level of deviation.”
That kind of mass loss would be extraordinary — and visibly dramatic.
“With such a huge mass loss — at least a tenth of the object’s total mass — it’s not just the surface layer or the skin being shed, but the body of the object itself becoming decimated.
“So, we should have seen a clear cometary tail, yet it’s not visible in the images that were released today.”
That apparent contradiction leads to Loeb’s most provocative suggestion.
“So the question is: what caused this non-gravitational acceleration?
“Of course, the alternative would be some kind of engine — and I’m just putting that on the table, because it is on the table. It’s not ruled out, and there are all these anomalies. And you know, that’s the beauty of it — that’s what makes science exciting.”
Loeb appears increasingly vindicated in his views.
On X last night, Representative Anna Paulina Luna — who has been pressing NASA for answers over its silence on 3I/ATLAS — said the agency confirmed Loeb’s early assessment of the object’s unusual, abnormal tail.
Luna has been seeking the release of high-resolution images captured by the HiRISE camera aboard the Mars Reconnaissance Orbiter on 2 and 3 October, which are believed to be around three times sharper than any publicly available image to date.
NASA has attributed delays in publishing the data to the recent government shutdown, a claim that has only deepened public scrutiny.
Investigating anomalies isn’t easy, and something not new to those investigating Unidentified Anomalous Phenomena (UAP).
For Loeb, the reaction to 3I/ATLAS feels familiar. He sees it as the same reflexive scepticism that UAP analysts often face — where even the most striking evidence is contorted to fit conventional models.
It’s a pattern he’s witnessed before, going back to the controversy surrounding another interstellar object, Oumuamua.
“When they tell you it’s an asteroid, or when they tell you it’s a comet,” Loeb said, “all they’re doing is working from very limited information. They see a source of light — and if it has a tail, it’s a comet. If it doesn’t, it’s an asteroid. That’s pretty much how they think.”
He says that when the data doesn’t conform neatly to expectations, the definitions themselves are simply rewritten.
“With ʻOumuamua, even though there was no tail — no gas or dust around it — they still declared it a comet, because it showed non-gravitational acceleration. So they called it a dark comet — a comet where you don’t see the feature that defines it as a comet.”
Then comes the punchline.
“It’s just like going to the zoo, looking at an elephant — and if you’re an expert on zebras, you say, ‘It’s a zebra without stripes.’”
The analogy lands because it captures his frustration: scientists redefining reality to preserve theory, rather than revising theory to match reality — a pattern he believes is now repeating with 3I/ATLAS.
Loeb’s observations may divide scientists, but they undeniably force a deeper question: how much of what we call knowledge is simply what we’ve agreed not to challenge?
For him, 3I/ATLAS is not just another interstellar rock — it’s a test of whether we’re still capable of genuine curiosity. In his view, the object’s behaviour remains unresolved and perhaps unpredictable.
When asked whether 3I/ATLAS could still change course — even toward Earth — he didn’t hesitate.
“It could,” he said.
“It needs to do it in the coming weeks, if. But you know, the fact that it doesn’t manoeuvre towards Earth could simply mean this: it’s a mothership that releases probes if it wants to acquire information on the planet. It doesn’t need to manoeuvre itself.
“And we don’t know the intent of any such visit [to our solar system] if it’s not a natural rock. What technology is it using? Why is it visiting? Whether it approaches Earth or not depends on its original intent. What is it trying to accomplish?”
It’s the kind of answer that lingers.
A reminder that in the vast silence of space, certainty may be the most dangerous illusion of all.
