3I/ATLAS Could Reach Earth? Harvard Scientist Explains Why Fragments Won't Land

A mysterious visitor from beyond our solar system may soon leave a lasting mark on our planet. Harvard physicist Avi Loeb suggests that the interstellar object known as Comet 3I/ATLAS could potentially deposit cosmic debris into Earth's atmosphere. This rare event offers a unique opportunity to study material originating from a distant star system.

The object reached its closest point to our globe on 19 December 2025, passing approximately 269 million kilometres away, making it only the third verified guest from another system. Experts watching its flight state this gap, nearly double the span between the Sun and us, is much too great for significant chunks to strike our world.

A Toxic Trail at a Safe Distance

Most significant anxiety for the general population and several experts stems from the specific ingredients found in the haze encircling 3I/ATLAS. Initial scans found traces of cyanide along with hydrogen cyanide in the atmosphere of the body, chemicals famously utilised for warfare a century ago.

Writing on Medium, Loeb clarified why these findings are not a threat. He noted that the solar wind—a flow of energised particles from the Sun—pushes aside most vapours within a short range of the visitor.

'This stopping distance is an order of magnitude smaller than the 55 million kilometres defining the minimum distance between 3I/ATLAS and the circle marked by the Earth's orbit around the Sun,' Loeb said. Consequently, he suggests that the vapours never have the range to reach our atmosphere.

When it comes to ultra-fine dust smaller than a micrometre, the pressure of sunlight would drive them off even more quickly. This almost entirely eliminates the possibility of such minute specks reaching Earth.

Why Even Solid Chunks Won't Survive

Solid pieces of the object, exceeding a millimetre, might hypothetically endure the solar wind and light pressure for a greater duration. Nevertheless, these objects would melt away in our atmosphere during entry, provided their dimensions remained well under a metre.

Regarding items over a metre wide that could potentially strike the surface, Loeb noted that such bodies are incredibly scarce. Judging by the calculated shedding of 3I/ATLAS, under a million of these substantial chunks have broken off lately—and regardless, 'their origin at a distance larger than about twice the Earth-Sun separation implies that the closest among them will never get closer than ten times the Earth's radius.'

This indicates that no sizeable wreckage released from the voyager could ever come close to touching our globe.

Where the Data Meets Debate

Loeb's findings are based on the premise that no pieces falling from 3I/ATLAS can move on their own through artificial means. He noted: 'This, of course, is under the assumption that the released objects cannot manoeuvre by technological propulsion.'

That point illustrates Loeb's habit of thinking outside the box. He is among the most prominent researchers willing to consider alternative views on 3I/ATLAS, suggesting it may not be an ordinary space rock. Elsewhere, he and his team have examined strange patterns in the body's movement and makeup, such as its peculiar emissions and shifting light levels.

Agreement Grows: Our Planet Stays Safe

Many scientists outside of Loeb's circle have concluded that 3I/ATLAS is almost certainly a standard icy entity. As noted by The Times of India, views from NASA-supported instruments have detected movements and discharges that align closely with what we expect from regular comets.

According to those statistics and projections, even the most minor remnants capable of withstanding solar pressure would almost certainly miss our atmosphere. If any pieces did find their way in, most would vanish into gas before they could ever impact the surface.

The Future of Interstellar Tracking

Even if 3I/ATLAS poses no threat to our planet, experts will be watching for other galactic voyagers with a sense of haste. These scarce bodies, starting with 1I/'Oumuamua in 2017 and 2I/Borisov in 2019, offer a one-of-a-kind look at the early building blocks of foreign systems.

For the time being, Loeb's verdict is clear: you should not anticipate any interstellar surprises from 3I/ATLAS appearing during the holidays—or at all.