The Other ATLAS Comet Breaks Apart As It Nears Earth

C/2025 K1 made its closest approach to the sun on October 8, descending to a distance of roughly 31 million miles—four times closer to the sun than 3I/ATLAS ever ventured. The intense thermal stress, rapid outgassing, and internal pressure swings typical of sun-grazing comets appear to have overwhelmed the nucleus. Early images taken soon after perihelion hinted that K1 might have survived, but those impressions have now shifted definitively. The new image confirms the nucleus has disintegrated, leaving only a streaming cloud of dust and rubble.

The fragmentation is consistent with well-studied cometary behavior. When the structural integrity of a comet’s interior cannot withstand heating and rotational stress, it breaks apart suddenly, often shedding pieces over a period of several days. C/2025 K1 now appears to be in that state: a dispersed field of reflective material, expanding slowly as solar radiation pushes the fragments outward.

The comet will make its closest approach to Earth later this month, though astronomers emphasize that the breakup poses no danger. Fragmentation does not redirect the comet’s path; instead, it diffuses its material along the original trajectory, lowering the mass concentration and making the object visually brighter in telescopes but physically harmless. The brightening is expected to continue as the surface area of the dust cloud increases.