It is a piece of chemistry born light years away, a rogue iceberg of cosmic material that pre-dates our own Sun. And for a brief, glorious period, it has been sailing through our celestial neighbourhood, giving scientists the once-in-a-lifetime opportunity to sample material from another star system.
The object is interstellar comet C/2025 N1, better known as 3I/ATLAS, and it has proven to be the most intriguing cosmic trespasser ever detected. Officially catalogued as only the third confirmed visitor from beyond our Solar System—following the famous 1I/ʻOumuamua and 2I/Borisov—this wandering ice ball was first discovered on July 1, 2025, by the NASA-funded Asteroid Terrestrial-impact Last Alert System telescope in Chile.
