Chinese scientists have confirmed that the rate of impact cratering on the near and far sides of the moon is consistent, a discovery that could significantly advance efforts to establish a globally unified lunar chronology system. The finding challenges long-standing assumptions about the moon’s early history and provides new insight into how its surface evolved over billions of years.
According to Chinese state media, the research was carried out by a team led by the Institute of Geology and Geophysics under the Chinese Academy of Sciences. The scientists revised a decades-old lunar impact crater chronology model by analyzing high-resolution remote-sensing images of the moon’s surface. Their work was published last week in the peer-reviewed journal Science Advances.
The study found that both hemispheres of the moon experienced a similar flux of asteroid and meteoroid impacts over time. This means the near side, which constantly faces Earth, and the far side, which remained largely unexplored until recent decades, share a comparable cratering history. Researchers say this uniformity provides strong support for building a single, globally applicable timeline to estimate the ages of different lunar surfaces.
Determining the age of the moon’s surface is essential for understanding its geological evolution. For decades, scientists have relied on crater counting as a key method for estimating surface ages. In general, areas with a higher density of impact craters are considered older, while smoother regions with fewer craters are thought to be younger. However, this method depends heavily on reliable reference models.
Until now, all crater chronology models were based exclusively on lunar samples collected from the near side of the moon. These samples, returned during earlier missions, date back no more than about four billion years. The lack of physical samples from the far side limited scientists’ ability to confirm whether impact rates were truly consistent across the entire moon.
This gap fueled long-running scientific debates about the moon’s early impact history. One of the most prominent theories, known as the Late Heavy Bombardment, proposed that the moon experienced a short but intense spike in impacts around four billion years ago. Other models suggested a more gradual decline in impacts over time. Without direct data from the far side, it was difficult to resolve these competing ideas.
China’s Chang’e-6 mission has played a crucial role in addressing this uncertainty. In June 2024, the mission successfully returned to Earth with 1,935 grams of lunar samples collected from the Apollo Basin within the South Pole-Aitken Basin on the moon’s far side. This marked the first time samples from this region were brought back for detailed laboratory analysis.
Scientists say data and samples from Chang’e-6 were instrumental in validating the revised crater chronology model. By combining sample analysis with remote-sensing observations, researchers were able to confirm that early lunar impact events followed a smooth and gradual decline rather than dramatic fluctuations. This finding weakens earlier claims of extreme bombardment episodes and supports a more stable model of lunar evolution.
The confirmation of consistent cratering rates across the moon has implications beyond lunar science. A unified lunar chronology system could also help scientists better understand the impact history of Earth and other rocky bodies in the solar system, as many early solar system events affected multiple planets and moons.
Researchers believe the study marks a major step toward resolving long-standing uncertainties about the moon’s past. As China and other spacefaring nations continue to explore the lunar surface and return more samples, scientists expect further refinements to lunar timelines, offering an increasingly clear picture of the moon’s formation and geological history.
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