A groundbreaking discovery beneath the Moon’s surface reveals a long-lived heat source that has stayed active for billions of years. Researchers have detected a persistent warmth coming from a huge granite mass tucked under the Compton and Belkovich craters. This heat isn’t from a current volcanic eruption; it’s a legacy of ancient volcanic activity that lingers now as a deep-seated radiogenic heat generated by the decay of radioactive elements contained in the granite. The results, published in Nature, indicate that the Moon’s interior continues to release heat long after its surface volcanism has faded.
Granite on the Moon: A Rare Find
Granite is a common volcanic rock on Earth, typically associated with volcanoes and plate tectonics. Finding it on the Moon is unusual and exciting. Dr. Matt Siegler, co-lead researcher at the Planetary Science Institute, explains that the detectable heat from this subterranean granite arises from radioactive decay occurring within the rock.
Unlike Earth, where granite forms through tectonic processes, the Moon’s granite likely cooled and solidified in a very different historical context. Using microwave observations—waves longer than infrared—sent to the Moon by the Chinese Chang’e 1 and 2 orbiters, scientists mapped temperatures beneath the surface. The team found that the Compton-Belkovich region “glowed” in microwave wavelengths, pointing to a subsurface heat source rather than active volcanic eruptions today.
A Distinct Lunar Volcano, Or So It Seems
The investigation uncovered a notable temperature difference: about 10°C (18°F) cooler surrounding terrain compared with the area beneath the craters. This thermal anomaly signals heat emanating from deep within the crust, suggesting that the Moon’s volcanic history may be more intricate than previously thought.
This work unveils a new kind of lunar volcanism. The Nature study identifies the Compton-Belkovich zone as a potential ancient volcanic caldera where long-lasting internal activity left behind signs of deep magmatic processes. While active eruptions aren’t evident now, the subsurface heat hints at a different mechanism at play—one rooted in radiogenic heating from a buried granite body.
Context from the Field
The 50-kilometer region appears to host a batholith—a large body of solidified magma that never breached the surface but cooled and crystallized within the crust, per geologist Dr. Rita Economos. The discovery challenges assumptions about how lunar volcanism operated and persisted over geological timescales.
Broader Implications
If similar granite-rich deposits exist elsewhere on the Moon, the extent of ancient volcanic activity could be broader than scientists have estimated. This finding invites fresh questions about the Moon’s thermal evolution and its geological history, as well as how heat from buried rocks shaped surface features long ago.
What this means for the Moon’s habitability and geological narrative remains an area of active research. The possibility of widespread ancient volcanism raises intriguing possibilities for interpreting the Moon’s interior and its past geologic dynamics.
