Rare interstellar visitor nears Earth this holiday season

Astronomers are getting a front-row seat to a cosmic spectacle this holiday season: Comet 3I/ATLAS, the third interstellar object ever discovered, will make its closest approach to Earth on December 19, likely the first time it has ever come near a star. 

Unlike objects bound to our solar system, interstellar visitors like 3I/ATLAS travel on hyperbolic paths, coming from distant star systems and continuing on their journey through the galaxy, Space.com writes. 

Formed in the outer reaches of another star’s protoplanetary disk, 3I/ATLAS was likely ejected by a massive exoplanet and has been wandering the Milky Way for billions of years. Observing it as it nears Earth offers astronomers an unprecedented chance to study its composition and gain insights into planet formation in other star systems.

Previous interstellar discoveries—1I/’Oumuamua in 2017 and 2I/Borisov in 2019—revealed that these visitors can differ significantly from our solar system’s comets.

For instance, 2I/Borisov’s high carbon monoxide content suggested it formed far from its star, much farther than comets in our own solar system. Early observations of 3I/ATLAS with the James Webb Space Telescope indicate it is enriched in carbon dioxide, hinting at a similarly distant origin.

For amateur astronomers, the close approach means that even small telescopes or powerful binoculars could catch a glimpse of this erratic wanderer. For scientists, it’s a rare chance to see interstellar material up close and to compare how comets form in other planetary systems versus our own.

By Sabina Mammadli