Did you know the Moon is shrinking? Yes, you read that right—our lunar neighbor is getting smaller, and it’s causing some fascinating geological drama. Scientists from the Smithsonian’s National Air and Space Museum have just unveiled the first-ever global map of small mare ridges (SMRs), a type of geological feature that reveals the Moon’s recent tectonic activity. Published in The Planetary Science Journal on December 24, 2025, this groundbreaking study shows that SMRs are not only widespread across the lunar maria—the dark, vast plains on the Moon’s surface—but also surprisingly young in geological terms. But here’s where it gets controversial: these findings suggest the Moon is more tectonically active than previously thought, which could mean more moonquakes than we’ve accounted for. What does this mean for future lunar missions? Let’s dive in.
Both the Moon and Earth are tectonically active, but their processes differ dramatically. Earth’s crust is divided into plates that collide, separate, and slide past each other, creating mountains, ocean trenches, and volcanic rings like the Pacific’s Ring of Fire. The Moon, however, lacks plate tectonics. Instead, stresses within its crust create unique landforms, such as lobate scarps—curved ridges formed when the crust compresses and pushes material upward along faults. These scarps, found in the lunar highlands, are relatively young, forming within the last billion years, or just 20% of the Moon’s history.
In 2010, senior scientist emeritus Tom Watters discovered that the Moon is slowly shrinking due to its cooling interior. This contraction is what causes lobate scarps to form. But lobate scarps aren’t the whole story. Enter SMRs—another class of tectonic landforms caused by the same forces but found exclusively in the lunar maria. And this is the part most people miss: while lobate scarps have been studied since the Apollo era, SMRs were largely overlooked until now.
Led by post-doctoral research geologist Cole Nypaver, the team mapped 1,114 new SMR segments across the nearside lunar maria, bringing the total known SMRs to 2,634. They found that the average SMR is around 124 million years old, similar to lobate scarps (105 million years old). These ages confirm that SMRs are among the youngest features on the Moon. The study also revealed that SMRs form via the same fault types as lobate scarps and often transition from highlands to maria, suggesting a shared origin. Together, these findings paint a more complete picture of the Moon’s recent contractional tectonic activity.
Here’s the kicker: SMRs are not just geological curiosities—they’re potential sources of moonquakes. Watters previously linked lobate scarps to moonquake activity, and since SMRs stem from similar tectonic forces, they could also trigger seismic events across the lunar maria. This expands the list of potential moonquake sources, offering new insights into lunar tectonics but also raising concerns for future human exploration. After all, seismic activity could pose risks to lunar bases or missions like Artemis.
‘We are in a very exciting time for lunar science and exploration,’ Nypaver said. ‘Upcoming missions will provide unprecedented data, and understanding lunar tectonics will be crucial for both safety and scientific success.’
So, what do you think? Is the Moon’s shrinking nature a game-changer for lunar exploration, or just another challenge to overcome? Let us know in the comments below!
For those eager to learn more, the National Air and Space Museum in Washington, D.C., offers a wealth of lunar exhibits. Located at 650 Jefferson Dr. S.W., it’s open daily (except December 25) from 10 a.m. to 5:30 p.m., with free admission but timed-entry passes required. The Steven F. Udvar-Hazy Center in Chantilly, Virginia, is also open daily (except December 25) from 10 a.m. to 5:30 p.m., with free admission, no timed passes, and $15 parking.
This material is edited for clarity and style. Views expressed are solely those of the author(s).
