Targets of opportunity sometimes happen in astronomy, and we got a major one when the third interstellar object, 3I/ATLAS, was discovered in July 2025. And it just so happens that in the intervening years between the last known interstellar visitor (2I/Borisov in 2019), we got a major upgrade in our observational capabilities with the launch of the James Webb Space Telescope (JWST). A new paper from a team of researchers led by Dr. Silvia Protopapa of NASA’s Goddard Space Flight Center and the Southwest Research Institute, and published in The Astrophysical Journal Letters, details JWST’s findings on the water ice content of this most recent visitor from beyond our solar system.

Typically, water ice is pretty easy to spot for astronomers. In infrared, which is JWST’s specialty, it absorbs light very clearly at 1.5, 2.0, and 3.0 microns in wavelength.…