The natural satellite of Earth is shrinking as its interior cools, driving moonquakes and landslides across the lunar surface according to a study published on Oct. 14, 2026, in The Planetary Science Journal, detikcom reported. Smithsonian and NASA researchers mapped over 10,000 faults using satellite imagery from the Lunar Reconnaissance Orbiter (LRO) to measure the contraction of the lunar radius by 42 to 46 meters over the past 400 million years.
Mapping Lunar Faults With LRO Imagery
Researchers identified 5,470 faults stretching longer than one kilometer across the lunar surface. Thomas Watters, the study’s lead author from the Smithsonian National Air and Space Museum, noted that the amount of young faults revealed in LROC imagery exceeds prior estimates. The cooling and shrinking of the lunar interior causes ongoing growth in existing faults and the formation of new ones.
Flat dark plains on the Moon contain ridges that contribute about six meters to the overall reduction in radius. On average, the lunar radius shrinks by 6 to 11 centimeters every million years. This rate remains invisible to the naked eye given the total radius of 1,737 kilometers.
Crust thickness controls surface stability during cooling
Scientists compare the lunar shrinking process to a drying grape turning into a raisin, though the crust behaves quite differently. Unlike the elastic skin of a grape, the lunar crust is hard and brittle. As the interior cools, the crust breaks and shifts upward to form thrust faults. Areas with thicker crusts tend to display fewer faults, pointing to a direct link between crust thickness and surface stability.
The resulting tectonic stress unleashes shallow moonquakes that reach up to 4 megapascal, or 40 times Earth’s atmospheric pressure. Data from 28 moonquake epicenters recorded by Apollo instruments during the 1970s revealed that 13 of those seismic events occurred within 90 kilometers of known fault scarps. Subsequent satellite comparisons have confirmed fresh landslide tracks near these active fault zones.
Seismic Risks for Future Human Exploration
NASA relies on these seismic and geological data to assess hazards for upcoming crewed missions and the construction of permanent lunar bases. Understanding fault locations allows mission planners to avoid seismically active zones when selecting landing sites.
Track lunar shrinkage and moonquake causes through satellite data
How much has the Moon shrunk?
The lunar radius has reduced by 42 to 46 meters over the past 400 million years, according to data published in The Planetary Science Journal on Oct. 14, 2026.
What causes moonquakes and landslides on the Moon?
Cooling of the lunar interior puts the brittle crust under intense pressure, causing it to break, form thrust faults, and release tectonic stress equivalent to 40 times Earth’s atmospheric pressure.
How do researchers track lunar shrinkage?
Scientists use satellite imagery from the Lunar Reconnaissance Orbiter to map thousands of small faults and cliffs across the lunar surface.
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