For a long time, people imagined the moon as a quiet, frozen world where nothing much happens anymore.
But new research shows that the moon is more active than we once thought.
Scientists have created the first global map of small ridges across the moon’s dark plains and discovered that these features formed relatively recently, suggesting the moon is still slowly changing.
The study, published in The Planetary Science Journal, focused on small mare ridges, low, narrow rises found in the lunar maria.
These maria are the large dark areas visible from Earth that formed billions of years ago from ancient lava flows.
Researchers from the Smithsonian’s National Air and Space Museum and their colleagues found that these ridges are widespread and surprisingly young in geological terms.
Unlike Earth, the moon does not have moving tectonic plates. On our planet, plate tectonics create mountains, earthquakes, and volcanoes as plates collide, pull apart, or slide past each other.
The moon’s crust is a single shell, but it still experiences stress. Over time, as the moon gradually cools, it slowly shrinks. This shrinking causes the crust to compress and buckle, creating ridges and cliffs on the surface.
Scientists already knew about similar features called lobate scarps, which appear mainly in the moon’s highlands.
These scarps form when the crust pushes upward along faults, creating steep ridges. Previous research showed that many of these formed within the last billion years, making them some of the moon’s youngest landforms.
The new study reveals that small mare ridges form in much the same way but are located in the maria instead of the highlands.
By carefully examining images from lunar orbiters, the research team identified more than a thousand new ridge segments on the moon’s near side, bringing the total known number to over 2,600. They estimated that these ridges are, on average, about 124 million years old — extremely young on the moon’s timeline.
The findings suggest that the same forces shaping the highlands are also affecting the maria, giving scientists a more complete picture of how the moon has been contracting over time.
In some places, ridges in the highlands appear to continue into the maria, reinforcing the idea that they share a common origin.
This discovery also has practical importance for future lunar exploration. Earlier studies linked tectonic features like lobate scarps to moonquakes — tremors that shake the lunar surface. If small mare ridges are formed by the same processes, they could also be locations where moonquakes occur. That means areas once considered safe might still experience seismic activity.
Understanding where these events might happen is especially important as space agencies prepare for new missions, including NASA’s Artemis program, which aims to return humans to the moon. Knowledge of the moon’s active geology can help engineers choose safer landing sites and design habitats that can withstand possible shaking.
The new global map of small mare ridges changes our view of the moon from a dead world to a dynamic one that is still evolving. As scientists continue to study these features, they hope to learn more about the moon’s interior, its history, and how it may behave in the future.
The moon may look calm from Earth, but beneath that quiet surface, it is still slowly reshaping itself.
