What interstellar comet, which made its closest approach to Earth in December 2025, was revealed by James Webb Telescope observations in March 2026 to be potentially 10-12 billion years old?

The interstellar (Review) comet 3I/ATLAS, a celestial wanderer from beyond our solar system, captured significant scientific attention as it journeyed through our cosmic neighborhood. This intriguing object made its closest approach to Earth on December 19, 2025, passing at a safe distance of approximately 168 million miles (270 million kilometers). Its hyperbolic trajectory confirmed its origin from interstellar space, making it only the third such object ever definitively observed by astronomers, following 1I/ʻOumuamua and 2I/Borisov.

The true marvel of 3I/ATLAS, however, unfolded in March 2026, when observations by the cutting-edge James Webb Space Telescope (Deals) (JWST) unveiled a startling revelation about its age. Scientists, analyzing isotopic measurements gathered by the JWST during the comet's flyby in December 2025, determined that 3I/ATLAS could be an astonishing 10 to 12 billion years old. This makes it potentially one of the most ancient objects ever detected in our solar system, predating our own sun and planets by billions of years.

This extraordinary age suggests that 3I/ATLAS originated in the early epochs of the Milky Way galaxy, potentially forming in a cold, distant region when the galaxy itself was still young. Studying such ancient interstellar visitors provides invaluable insights into the conditions and chemical environments of the early universe and the formation of planetary systems around other stars. While 3I/ATLAS is now rapidly departing our solar system, its brief visit and the subsequent JWST observations have left an indelible mark on our understanding of cosmic history.