Will Toxic Materials, Including Cyanide, From Interstellar Comet 3I/ATLAS Reach Earth? Expert Reacts

The interstellar comet 3I/ATLAS contains cyanide and hydrogen cyanide, which are highly toxic substances.

24 Dec 2025, 17:48 · www.ndtv.com

The interstellar comet 3I/ATLAS made its closest approach to Earth recently on December 19, and apparently caused no harm, passing at a safe distance of 269 million kilometres. But many still wonder if any of its material would reach us. Previous observations found that 3I/ATLAS contains cyanide and hydrogen cyanide, highly toxic substances that were used as chemical weapons in World War I.

But experts say there's no need to worry as the solar wind will sweep up these gases at a distance of just a few million kilometres from the comet, well before they can reach Earth.

Also read | Farewell To 2025: A Year When An Interstellar Visitor Became Global Obsession

"Dust particles which are smaller than a micrometer would be swept away even faster by the solar radiation pressure," said Harvard physicist Avi Loeb in a blog post on Medium.

"However, solid particles or objects that are bigger than a millimeter have a sufficiently small cross-section per unit mass to continue along their path, largely unaffected by the solar radiation or wind."

Also read | Green And Purple Auroras Are Lighting Up Skies Far Beyond The Poles, Here's Why

Considering the mass loss rate of the comet, Loeb said that fewer than a million large objects, bigger than 1 meter, were released, and their trajectories ensure they'll stay far clear of Earth. Meanwhile, the small particles, smaller than 1 meter, will burn up in Earth's atmosphere before reaching the ground.

"...an enhanced flux of millimeters scale particles from 3I/ATLAS could be collected by a space experiment on a satellite or the space station above the dense part of the Earth's atmosphere. It would be particularly exciting to design and exiecute such an experiment in the coming months," Loeb said.

Show full article

Track Latest News Live on NDTV.com and get news updates from India and around the world