New findings indicate that the Moon is still undergoing geological changes, challenging the long-held belief that it is a geologically inactive body. In a study published in The Planetary Science Journal, researchers revealed evidence suggesting that what lies beneath the lunar surface may be more dynamic than previously believed.
Researchers from the University of Maryland found evidence suggesting the Moon is geologically active, including the discovery of 266 previously undocumented small ridges on the far side. These ridges were identified in volcanic regions estimated to have formed 3.2 to 3.6 billion years ago. They typically appear in groups of 10 to 40 and are often located in narrow areas with underlying weaknesses in the Moon's surface.
"Many scientists believe that most of the Moon's geological movements happened two and a half, maybe three billion years ago," said Jaclyn Clark, Assistant Research Scientist at the University of Maryland's Department of Geology. "But we're seeing that these tectonic landforms have been recently active in the last billion years and may still be active today. These small mare ridges seem to have formed within the last 200 million years or so, which is relatively recent considering the Moon's timescale," she added.
The research team employed crater counting to estimate the ages of the small ridges. "Essentially, the more craters a surface has, the older it is; the surface has more time to accumulate more craters," Clark explained. By analyzing the craters around these ridges and observing that some ridges cut through existing impact sites, the team concluded that these formations were active within the last 160 million years.
Some of the ridges on the Moon's far side formed over new impact craters. These small ridges are younger than other known lunar surface features, suggesting a recent formation caused by recent activity.
The similarity of the ridges suggests they were created by the same forces. According to IFLScience, these forces are likely a combination of the Moon's gradual shrinking and thermal contraction, as well as shifts in its orbit. Observations suggest that the ridges on both the near and far sides of the Moon may have originated from the same geological processes.
Decades-old data from Apollo missions had previously detected shallow moonquakes. The Apollo Lunar Seismic Experiment recorded 28 shallow moonquakes with magnitudes of approximately 1.5 to 5. Researchers now believe these ridges may be linked to similar seismic events. Science Daily reports that the epicenters of shallow seismic events were spatially correlated with the locations of lobate scarps in the lunar highlands.
The identification of active geological processes on the Moon implies it is not a static body. This has implications for the logistics of future missions, particularly for those investigating subsurface structures and the current seismic state of the Moon.
"These landforms are products of ongoing tectonic forces on the Moon, indicating that geological processes are still occurring," Clark said. The discovery of these ridges challenges the understanding of the Moon's geological timeline and suggests that the Moon is more geologically active than previously assumed.
The article was written with the assistance of a news analysis system.