Mysterious Color Shift of Interstellar Comet 3I/ATLAS

The Mysterious Color Shift of 3I/ATLAS

Interstellar object 3I/ATLAS recently stunned astronomers by changing its coma color from red to green as it neared the Sun. While green glows in comets are often linked to diatomic carbon molecules fluorescing under ultraviolet light, 3I/ATLAS challenges this explanation because it appears depleted in such carbon chains. This suggests other chemical processes or compounds are responsible for its emerald hue.

Possible Causes Behind the Green Glow

One compelling theory comes from Harvard’s Avi Loeb, who proposes that the green color results from a sharp increase in cyanide production detected by the Very Large Telescope. Cyanide and possibly nickel emissions might be intensifying due to solar heating, altering the comet’s visible spectrum. The exact chemistry remains uncertain, highlighting the object's unique nature.

Significance and Ongoing Observations

3I/ATLAS is not only remarkable for its color change but also for its massive nucleus and interstellar origin. As it moves behind the Sun soon, astronomers anticipate a temporary observational gap, but further studies will continue once it reemerges, promising deeper insights into this extraordinary cosmic visitor.