The Hidden Ocean of Ariel: Tidal Forces and the Case for a Watery Past

Could Uranus's moon Ariel have once harbored a vast, deep ocean beneath its icy crust—perhaps even one that still lingers today? In this episode of SETI Live, host Beth Johnson welcomes Caleb Strom (University of North Dakota) and Alex Pathoff (Planetary Science Institute) to discuss new research revealing evidence that Ariel may have once held a subsurface ocean over 170 kilometers deep. Using geological mapping and tidal‐stress modeling, the team shows how ancient fractures and ridges on Ariel's surface hint at powerful internal forces and a dynamic, watery past. This discovery expands the growing family of "ocean worlds"—planets and moons that may have once supported (or could still support) conditions for life. What does this mean for future exploration of the Uranus system, and what could we learn by going there? 🔗 Press release: https://www.psi.edu/blog/evidence-of-a-past-deep-ocean-on-uranian-moon-ariel/  📄 Paper: https://www.sciencedirect.com/science/article/abs/pii/S0019103525003707 (Recorded live 23 October 2025.)