While observing the Halley-type comet 12P/Pons-Brooks with ALMA and NASA's Infrared Telescope Facility, researchers determined that the comet's water is strikingly similar to the water on Earth.
In the past decade, astronomers have witnessed three interstellar objects (ISOs) passing through the Solar System. This included the enigmatic 'Oumuamua in 2017, the interstellar comet 2I/Borisov in 2019, and 3I/ATLAS in July 2025. This latest object also appears to be a comet based on recent observations that showed it was actively releasing water vapor as it neared the Sun. The detection of these objects, which were previously theorized but never observed, has piqued interest in the origins of ISOs, their dynamics, and where they may be headed once they leave the Solar System.

