JWST Finds Water Ice in Interstellar Object 3I/ATLAS

The James Webb Space Telescope found water ice in 3I/ATLAS, an object that came from beyond our solar system.

Discovered in July 2025, it was the third known interstellar object to pass through our solar system.

Earlier observations showed an unusual infrared pattern, leading some observers to question whether the object contained water ice.

Researchers modeled light passing through particles made of ice mixed with dust and found that this explained the pattern.

The ice is mixed with dark rocky minerals in tiny grains, which weakens some infrared signals and makes the object appear blue.

After the object passed closest to the Sun, observations also showed signs of crystalline ice and larger ice-rich grains.

These findings suggest water ice behaves in familiar ways beyond our solar system, while showing how its structure can vary.

The researchers proposed that solar heating or the removal of outer dust may have revealed the crystalline ice after the object's closest approach to the Sun.