In recent years, our knowledge of the Moon and its geologic history has expanded considerably. Recently, astronomers discovered something amazing beneath the Compton and Belkovitch craters on the back side of the Moon–a large mass of granite that was slowly releasing heat. This means that there was ancient volcanism on the Moon, which changes the way we think about the Earth’s satellite.
Granite is a rock that forms deep beneath the Earth’s surface, usually under a volcano, where magma can cool and crystallize. Water and plate tectonics are needed to form granite. Therefore, finding granite on the Moon is a unique and interesting discovery.
Researchers used data from Chinese and U.S. lunar orbiters to locate this heat-emitting mass beneath the surface of the Moon. Using an instrument that studies microwave waves, they were able to map the temperatures below the surface and discovered that the Compton-Belkovitch crater glows completely in the microwave range. This indicates that the heat source is not on the surface, but deeper underground.
Dr. Matt Sigler of the Institute of Planetary Science notes: “The only way to explain this is additional heat coming from somewhere underneath the object in the deeper lunar crust. So Compton-Belkovich, thought to be a volcano, is also hiding a large source of heat underneath.”
The data show that beneath the Compton-Belkovich crater is a silicon-rich surface, 20 kilometers wide, which is the caldera of this ancient volcano. Temperatures in this area are 10°C higher than in the surrounding environment, but this is not due to magma beneath the surface. The last time this volcano erupted was 3.5 billion years ago. The reason for the elevated temperature is due to radioactive elements trapped in the rocks.
Dr. Ziegler explains, “We interpret this heat flow as the result of a radiogenic-rich granite body beneath the caldera. This find represents a 50 km wide batholith, which forms when lava rises into the Earth’s crust but does not erupt to the surface.”
However, the presence of such a large deposit of granite on the Moon raises questions. Perhaps there are other areas of the Moon where granite can be found. Researchers speculate that similar processes may have occurred elsewhere in the solar system.
The discovery of ancient volcanism on the Moon changes our understanding of Earth’s satellite. It gives us a better understanding of the Moon’s geological history and evolution. It also opens up new perspectives for future studies of the Moon and other celestial bodies.