Internal Heat Flux and Energy Imbalance of Uranus

With its extreme axial tilt, Uranus' radiant energy budget (REB) and internal heat flux remain among the most intriguing mysteries in our solar system. By combining observations with modeling, we present the global REB over a complete orbital period (1946–2030), revealing significant seasonal variations. Despite these fluctuations, the global average emitted thermal power consistently exceeds absorbed solar power, indicating a net energy loss. Assuming no significant seasonal variation in emitted power, we estimate an internal heat flux of 0.078 ± 0.018 W/m2 by analyzing the energy budget over one orbital period. The combination of internal heat and radiant energies indicates substantial global and hemispheric imbalances, with excesses or deficits exceeding 85% of emitted power at the hemispheric scale. These findings are crucial for understanding Uranus' interior and atmosphere. A future flagship mission to Uranus would provide critical observations to address more unresolved questions of this enigmatic ice giant.