Earth's Gravity May Have Fueled Moon Volcanoes
Researchers propose tidal heating from Earth's pull explains volcanic basalts on the Moon about two billion years old.
Updated on Nov. 6, 2026 in Geology
A research team proposes that tidal heating generated by Earth's gravity powered volcanic activity on the early Moon. The proposal aims to explain basalt samples returned by China's Chang'e-5 mission that are about two billion years old.
Why it matters
Traditional geological theory predicts the Moon should have cooled rapidly after forming, so volcanism two billion years later is unexpected. The proposed mechanism offers a way to reconcile that expectation with the age of the returned samples.
The mechanism rests on a convection simulation and laboratory dating rather than direct observation of the mantle. Tidal heating delivered about 150 gigawatts to two symmetric anomaly zones along the core-mantle boundary, more than four times the heat supplied by radioactive decay, though the study's direct confirmation remains unresolved.
The players
Chang'e-5
China's lunar sample-return mission that collected basalts from Oceanus Procellarum and returned them to Earth for laboratory analysis.
The details
Tidal heating occurs when a body is stretched and squeezed while orbiting a larger body on an elliptical path. Simulations identified two symmetric Tidal Heating Anomaly Zones along the lunar core-mantle boundary, where an ultra-low viscosity rock layer may have melted pockets of mantle that later formed basalt.
Timeline
About 4.5 billion years ago: Theia collided with early Earth, forming the Moon.
About 3.2 billion years ago: Tidal strain delivered 150 gigawatts to the anomaly zones.
About 2 billion years ago: Basalts later sampled by Chang'e-5 formed from melted mantle pockets.
Over the next decade: Numerous planned lunar missions may provide more definitive data.
Big Picture
The proposed lunar mechanism extends the known pattern of tidally driven volcanism observed on Jupiter's moon Io, where Jupiter's gravity powers ongoing eruptions. Applying the same principle to Earth's Moon reframes early lunar volcanism as a product of planetary gravitational forces rather than residual internal heat alone.
Confirming tidal heating as a driver of lunar volcanism would refine how scientists date and interpret samples from the Moon. The work also informs models of how planetary bodies retain or lose internal heat over billions of years.
The takeaway
Gravity from neighboring bodies can keep a world geologically active long after its formation, challenging simple cooling models. Tracking how tides shape interior heat is a useful lens for reading planetary histories.
What happens next
Numerous lunar missions are planned over the next decade and may provide more definitive data on the proposed mechanism.
Further reading
Explore more on Geology to see how planetary forces shape the rocks beneath our feet.
