Key Takeaway:
China’s Chang’e 5 mission has challenged long-held assumptions about the Moon’s volcanic past, suggesting eruptions occurred far more recently than expected. The lunar landscape might not have been as dormant as once believed, with volcanic activity on the Moon potentially being active as recently as 120 million years ago. The findings suggest that certain regions of the Moon’s interior, like the landing site of Chang’e 5, could be enriched with radioactive elements, which generate heat, possibly prolonging volcanic activity in specific areas. The lunar landscape, known as maria, was once thought to have cooled and solidified, but new data from the Chang’e 5 mission in 2020 suggests that volcanic activity continued far longer than previously thought. This discovery could lead to new insights into the behavior of other celestial bodies and the Moon’s volcanic history.
For centuries, humans have gazed at the Moon, mesmerized by its calm, cratered surface. However, recent evidence suggests that the lunar landscape might not have been as dormant as once believed. New data from China’s Chang’e 5 mission challenges our long-held assumptions about the Moon’s volcanic past, suggesting eruptions occurred far more recently than expected—potentially shaking up our understanding of lunar history.
Volcanic activity, it was long assumed, ceased on the Moon about 2 billion years ago. This belief was based on the analysis of rock samples collected during the Apollo missions and Soviet robotic probes. But Chang’e 5, which touched down on the lunar surface in 2020, returned with rock and soil samples that tell a different story. Published in Science, these new findings indicate that volcanic activity on the Moon might have been active as recently as 120 million years ago, a timeline that dramatically shifts our understanding of lunar geology.
This discovery adds an intriguing new twist to the history of lunar volcanism. While the findings are difficult to reconcile with previous models, they suggest that certain regions of the Moon’s interior, like the landing site of Chang’e 5 in Oceanus Procellarum, could be enriched with radioactive elements. These elements generate heat, possibly prolonging volcanic activity in specific areas.
Eruptions Across the Solar System
Volcanism is a critical mechanism by which rocky planets and moons release heat, shaping their surfaces and sometimes even their atmospheres. In our solar system, Earth, Venus, Mars, Mercury, Jupiter’s moon Io, and our Moon have all experienced volcanic activity to varying degrees.
Venus remains volcanically active, and scientists have observed lava flows on Mars that suggest the planet could still experience eruptions every few million years. This makes sense, given that larger planets like Earth and Mars can conserve heat better than smaller bodies. Mercury and the Moon, much smaller by comparison, were long believed to have become volcanically inactive around 2 billion years ago.
Io, despite being similar in size to our Moon, is a different story altogether. The gravitational pull from Jupiter exerts immense tidal forces on Io, creating a powerful heat source that drives its constant volcanic activity. The Moon, lacking such a source of external heat, was presumed to have gone cold—until now.
A Dark and Fiery Past
The Moon’s most striking features are the vast, dark patches on its surface known as maria, named by early astronomers who mistook them for seas. These maria were created by ancient lava flows that filled the interiors of giant impact craters. For decades, the scientific consensus was that these lava flows marked the last of the Moon’s volcanic activity, which had long since cooled and solidified.
That understanding held until NASA’s Lunar Reconnaissance Orbiter began sending back high-resolution images in 2009. The new images revealed regions on the Moon, known as irregular mare patches (IMPs), that lacked the number of impact craters one would expect on a surface billions of years old. Instead, these regions appeared to be relatively young, only about 100 million years old, suggesting more recent volcanic activity than previously thought.
The crater-counting method, long used to estimate the age of planetary surfaces, came under scrutiny. Some scientists speculated that the Moon’s lack of atmosphere could explain these discrepancies. Without atmospheric pressure, lunar lava flows may have been porous and foam-like, creating surfaces more easily eroded by impacts, which would give the false impression of youth.
Chang’e 5 Brings New Clues
In 2020, the Chang’e 5 mission returned with lunar samples from a previously unexplored region of Oceanus Procellarum, a vast lunar basin thought to have experienced significant volcanic activity. While initial analyses of the samples aligned with previous theories of a 2-billion-year cutoff for lunar volcanism, a closer look revealed something startling.
Scientists identified volcanic droplets—tiny fragments of volcanic glass—in the sample that date back only 120 million years, suggesting that volcanic eruptions continued far longer than previously thought. These droplets are likely remnants of explosive volcanic activity, similar to the lava fountains seen in Hawaii today, and could have traveled across vast distances from their source.
Revisiting the Moon’s Fiery History
These findings challenge long-standing theories about the Moon’s evolution. If volcanic activity persisted until just 120 million years ago, scientists must reconsider the heat dynamics within the Moon’s interior. The most plausible explanation is that certain areas of the Moon, like Oceanus Procellarum, contain higher concentrations of radioactive elements. These elements could have provided the heat necessary to sustain volcanic activity much longer than expected.
This discovery not only reshapes our understanding of the Moon’s past but could also lead to new insights about the behavior of other celestial bodies. Just as Earth’s surface is shaped by its molten core, the Moon’s volcanic history could hold clues about how planets and moons across the solar system cool and evolve.
As new missions return more lunar samples and advanced techniques allow for even more precise measurements, we may find that the Moon, long considered geologically dead, was active far more recently than anyone had imagined. These new revelations could force us to rewrite textbooks and rethink our understanding of the Moon’s fiery past.
