Tidal heating
Frictional dissipation of orbital and tidal energy as heat inside a planetary body. Tidal heating is the physical mechanism that keeps liquid water in subsurface oceans on icy moons over geologic time and that drives the most extreme volcanism in the solar system.
In the solar system
- io — orbital resonance with Europa and Ganymede produces flexural heating sufficient to power continuous silicate volcanism and km-tall plumes.
- Europa — tidal heating maintains a global subsurface liquid-water ocean and drives ice-shell tectonics.
- enceladus — south-polar plume activity and hydrothermal-activity are powered by tidal flexing and core-mantle friction.
- triton — possible subsurface ocean maintained by tidal heating from Neptune capture-orbit eccentricity, plus radiogenic heating.
Exoplanet relevance
The 2026 NCCR PlanetS active-moons review (src-active-moons-review-2026-04) extends this physics to exomoons — Io-like volcanic outgassing on exomoons would be powered by analogous tidal mechanisms and may be detectable from ground-based telescopes.