Distant planets are missing some key chemicals, which means their insides are hundreds of degrees hotter than we thought was possible.
April 3, 2026
Original Paper
Unusually Hot Interiors Could Reconcile the Missing Methane Problem for Warm-to-Hot Exoplanets with Hydrogen Atmospheres
arXiv · 2604.01672
The Takeaway
The James Webb Space Telescope found several exoplanets with almost no methane, which contradicts basic chemistry unless the planets are incredibly hot inside. This suggests that our entire model of how planets form and cool down over billions of years is fundamentally missing something.
From the abstract
JWST is revolutionizing the field of exoplanet atmospheres by delivering unprecedented spectroscopic constraints on their chemical compositions. It has provided tight constraints on the abundances of dominant carbon- and oxygen-bearing species on numerous warm-to-hot exoplanets with hydrogen-dominated atmospheres. Under thermochemical equilibrium, many of these exoplanets should have abundant methane (CH4); however, CH4 has, so far, only been spotted in a few cases. Here, we present a simple, ge