New Delhi: The interstellar traveller 3I/ATLAS—only the third confirmed object known to arrive from beyond our Solar System—has sparked a wave of excitement among astronomers around the world. First spotted on July 1, 2025, by the ATLAS survey telescope in Chile, the comet, officially designated C/2025 N1 (ATLAS), is racing through space on a hyperbolic trajectory that confirms its alien origin. Entering our skies from the direction of Sagittarius, it hurtles through the void at a velocity no ordinary comet could sustain—untethered by the Sun’s gravity and destined to vanish forever into the dark between the stars.
As it draws nearer to the Sun—reaching its closest point around October 30 at roughly 1.4 astronomical units, just inside Mars’ orbit—3I/ATLAS will not approach Earth. Yet even its fleeting passage offers scientists a remarkable chance to study material forged around another star. It is, quite literally, a messenger from a different world, carrying the elemental fingerprints of an alien system.
What has particularly intrigued astronomers is the comet’s unpredictable behaviour. Unlike typical comets, which brighten slowly as they approach the Sun, 3I/ATLAS has flared in brightness much faster than expected. Observations from the James Webb Space Telescope have revealed a highly unusual chemical makeup—its coma appears rich in carbon dioxide but nearly devoid of water vapour and other familiar volatiles. This composition suggests it formed in a frigid, far-flung region of its parent system, perhaps even beyond the icy boundaries where comets in our own Solar System are born. Its nucleus may be immense—ten kilometres wide or more—making it one of the largest interstellar visitors ever recorded.
For planetary scientists, 3I/ATLAS offers a rare, tangible link to other solar systems. Each measurement of its brightness, rotation, and spectrum deepens our understanding of how differently other worlds may have formed. The discovery also raises unsettling questions: if such massive bodies can wander into our cosmic neighbourhood, how many others might be passing silently through the interstellar void, unseen?
Even now, the comet remains a challenge to observe. Its faintness and distance mean only the most powerful telescopes can capture it. Some astronomers have noted subtle irregularities in its motion—small deviations from predicted gravitational paths—fueling speculation about outgassing, fragmentation, or forces still unexplained. While such theories remain speculative, the fascination endures. Space agencies are already redirecting instruments, from the Hubble Space Telescope to Mars orbiters, to gather every possible scrap of data before it slips away.
Soon, 3I/ATLAS will swing past the Sun, dim, and disappear forever into the depths of space. Yet its brief visit will leave behind something precious: clues to the chemistry and history of worlds born around other suns.
As it glides beyond Mars’ orbit, humanity watches in wonder. This is more than a comet—it is a traveller from another star, carrying whispers of places we may never see, crossing the silence between worlds.
