The Moon Rumbled When Dinosaurs Roamed the Earth

Scientists have analyzed some of the lunar samples brought back by China's Chang'e 5 mission in 2020 and identified signs that volcanic activity existed on the Moon as recently as 120 million years ago. This volcanic activity could still be happening today.

Traces visible from Earth

We already knew that the Moon had experienced active volcanism in the past. The lunar maria, these immense dark spots visible from Earth and covering 16% of the surface of our natural satellite, are proof of this. These large basaltic plains were partly formed by ancient volcanic flows around 3.8 billion years ago. However, it was thought that this was the last time that the Moon was volcanically active.

From volcanism to the time of the dinosaurs

This is not the case, as recent discoveries obtained through the analysis of glass beads contained in samples brought back by the Chang'e 5 mission attest. Volcanic eruptions are thought to have taken place on our neighboring star 123 million years ago, with a margin of plus or minus 15 million years.

From the perspective of our short human lives, 123 million years seems like an eternity, but geologically it is not. This means that the Moon may have been volcanically active throughout its existence and may still be so today.

Marbles in a regolith bundle

Signs of this volcanic activity were found in only three small glass beads, among the 3,000 contained in the samples brought back by Chang'e 5. These three balls were discovered by researchers from the Chinese Academy of Geology and Geophysics in a sample of dust weighing just 1.7 g.

These beads, ranging in size from 20 to 400 µm, can be formed by violent meteorite impacts, which heat and compress the rock to the point of making glass. While almost all of these beads are formed this way, it is not the only way to obtain them; magma fountains also produce them. Glass beads of volcanic origin have already been found on the Moon in the past, but all came from eruptions several billion years old. Dating by uranium-lead technique of the three glass beads, on the other hand, shows that they are only about 123 million years old.

Understanding the origin of this volcanism

This discovery is surprising, because according to our current models of the evolution of our natural satellite since its formation, it should have cooled so long ago that we do not expect to find volcanism so recent. So what could be its origin?

According to scientists,
radioactive decay of certain elements such as potassium or phosphorus, which could generate enough heat to melt the rocks of the lunar mantle and cause small eruptions. Of course, these results will have to be confirmed by new explorations and analyses.