Groundbreaking Moon To Moon Tidal Resonance Discovery

By: Noemi Elliott

Based on the understanding that a certain amount of heat is required to keep an ocean wet, a new analysis suggested that Juptier’s moons can act as sources of heat for each other. Jupiter’s four largest “Galilean” moons – Ganymede, Callisto, Europa, and Io– were examined in the study.

Ganymede, Callisto, and Europa were hypothesized to harbour liquid water underneath the surface while Io contains an inner magma ocean, all relying on heat in the process. Until recently, scientists focused on the impact of Jupiter’s size and gravitational pull to explain the heating of the planet’s moons.

“Jupiter’s gravity stretches and squeezes these moons as they orbit the gas giant, heating their interiors through friction,” explained astronomers in a research paper. “It is essential to understand this process, known as tidal heating, given the unique geophysical structure of ocean worlds and their potential for habitability.”

Now, the effect of each moon’s gravitational pull on the other has been taken into consideration. Investigating the moon-moon tides in the Galilean moons, a group of NASA scientists determined that tidal waves created significant heating in their individual subsurface oceans.

“The heating occurs both in the crust and ocean and can exceed that of other tidal sources and radiogenic decay if the ocean is inviscid enough. The resulting tidal deformation can be used to constrain subsurface ocean thickness,” wrote NASA scientists.

Through modeling subsurface tidal currents, researchers determined that the ocean’s corresponding resonant response manifests through tidal waves. Looking forward, understanding of the evolution of the workings of ocean worlds within a compact system may be altered by the observations of moon-moon tidal resonances. Additionally, exploration of habitable living conditions beyond Earth may also be aided by this discovery.

“We have good reason to predict that at least six moons of the outer solar system likely harbor liquid water oceans beneath their icy crusts… throughout the history of the solar system, ocean worlds may have come and gone… If we really want to understand what makes any alien organism tick, then we need to find life that is alive today and that requires the presence and persistence of liquid water,” observes Kevin Hand in his book Alien Oceans: The Search for Life in the Depths of Space.

https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020GL088317

The Galilean Moons of Jupiter

Jupiter’s moons could keep each other warm by raising tidal waves