Using the JWST space telescope, astronomers conducted a chemical analysis of the centaur Chiron, an icy body from the fringes of the Solar System. It turns out its gas activity resembles a layered cake. Carbon dioxide evaporates from the surface, forming a top crust. Deeper down, like a filling, methane seeps out. And at the very core, carbon monoxide lurks — frozen solid because heat barely reaches it.
This layering points to a complex interior, where each layer evaporates at a different temperature. JWST has revealed this chemical stratification in detail for the first time, showing that icy wanderers “breathe” in different ways. On Chiron, methane and carbon dioxide even form separate, unmixed clouds. This shifts our picture of how such bodies shed mass.
On most active asteroids and comets, carbon monoxide is the primary gas. Chiron defies the norm: here, methane dominates, while carbon monoxide stays locked inside.