What is the mysterious acceleration of comet 3I/ATLAS that’s dividing scientists?

The interstellar comet 3I/ATLAS, which we’ve already covered here on viraltrendingcontent, is making headlines once more – and this time, for something even stranger.
A new and unexpected change in its trajectory has left scientists scratching their heads, reigniting debates over whether we’re witnessing a perfectly natural cosmic event… or something far more mysterious.

A cosmic wanderer behaving oddly

Fresh observations from Chile’s ALMA radio telescope array have revealed that 3I/ATLAS isn’t exactly where physics said it should be. In other words, it’s not following the neat, predictable curve expected under the pull of gravity alone.
Instead, it appears to be experiencing what experts call “non-gravitational acceleration” — a small but measurable force nudging it off its expected path, particularly noticeable when it passed closest to the Sun.

Now, before you imagine alien spacecraft engines firing up, the most straightforward explanation is still a natural one. When comets get close to the Sun, they tend to release gas and dust, creating a tiny thrust — a bit like a cosmic jet.
But there’s a catch. If that’s what’s happening here, scientists should see a huge cloud of vapour and debris around it. So far, nothing like that has shown up.

Over the next few months – between November 2025 and January 2026 – telescopes including Hubble, James Webb, and the International Asteroid Warning Network will be watching closely. If this predicted cloud doesn’t appear, things could get very interesting indeed.

Echoes of a past mystery: remember ‘Oumuamua?

This isn’t the first time something like this has happened.
Back in 2017, the world’s first known interstellar visitor, 1I/‘Oumuamua, puzzled scientists in exactly the same way. It also seemed to accelerate slightly without any visible sign of gas or dust — the kind of behaviour that left experts utterly baffled.

Unlike a normal comet, ‘Oumuamua had no visible tail, no dust trail, nothing to explain why it sped up. Some even jokingly called it a “dark comet” – though the idea of a comet without a tail is like having a campfire without smoke.

Now, 3I/ATLAS seems to be following in its footsteps.
Its acceleration, estimated at around 0.02 thousandths of a metre per second squared, suggests it somehow lost an enormous amount of mass in a very short time – possibly around 5.5 billion tonnes of material.
Yet, strangely, before October this year, even the powerful James Webb Telescope detected no such activity, despite tracking a steady mass loss of around 150 kilograms per second.

Science divided: natural phenomenon or something else?

Not everyone agrees on what’s going on.
For some astronomers, 3I/ATLAS’s odd movement is just another example of cometary behaviour we don’t fully understand yet. But others — including Harvard astrophysicist Avi Loeb – think it might be time to at least consider a different possibility.

Loeb, who stirred controversy years ago by suggesting that ‘Oumuamua might be of technological origin, says this new object is worth the same scrutiny.
“If by December we don’t see the predicted gas cloud,” Loeb said, “then we must consider the possibility of an artificial propulsion source.”

That remark has reignited a familiar debate – especially after British physicist Brian Cox dismissed the idea outright, insisting the object’s behaviour is purely natural.

Loeb hit back, noting that Cox hasn’t published any scientific studies on the object, while he himself has written more than a dozen peer-reviewed papers on its anomalies.
“For me, science isn’t decided by applause or television charisma,” he said. “It’s decided by rigorous analysis of data. And the data, in this case, don’t quite fit our usual explanations.”

According to Loeb, the facts are simple but striking: 3I/ATLAS is unusually bright, more blue than the Sun, and appears to be moving in a way that gravity alone can’t explain.

A question that goes beyond science

So what exactly is pushing 3I/ATLAS?
Is it just ice and gas reacting to sunlight in a way we haven’t fully modelled? Or is it something stranger – perhaps even artificial in nature?

For now, the answer remains out of reach. But one thing’s for sure – this mysterious visitor from beyond our solar system is forcing us to look at the universe with fresh eyes.

As Loeb put it, the question isn’t whether 3I/ATLAS is a spacecraft. The real question is: why is it moving as if something is pushing it?

Maybe the explanation will turn out to be perfectly ordinary. But if it doesn’t, we could be witnessing something truly extraordinary – a quiet, almost imperceptible moment in history where we realised we might not be as alone as we thought.

A tiny shift, just a few seconds of arc, that could one day change the way we see our place in the cosmos.