Brief
Study finds Moon’s radius shrank about 148 feet over hundreds of millions of years
Lunar Reconnaissance Orbiter data reveal more than 10,000 young cracks, allowing researchers to quantify the Moon’s gradual contraction.
By Felo News Desk · Published
Scientists examining images from NASA’s Lunar Reconnaissance Orbiter Camera (LROC) have identified more than 10,000 young faults on the Moon’s surface and estimate that the lunar radius has decreased by about 148 feet (45 meters) over the past 400‑800 million years, according to space.com.
What happened
The research team mapped lobate scarps – long, curved ridges that form as the Moon’s crust contracts – and small mare ridges, narrow wrinkles on the dark basaltic plains. By counting these features, the scientists concluded that the Moon’s single‑plate outer shell has been steadily shrinking as its interior continues to cool from the ancient impact that formed it.
What the reports add
Space.com notes that the number of young faults revealed in LROC images far exceeds earlier expectations. The study distinguishes two main fault types: over 8,900 lobate scarps (red lines on the global map) and more than 2,000 small mare ridges (blue lines). The distribution of faults is uneven, with some regions showing a higher density of cracks.
What was said
"The number of these young faults revealed in LROC images is much greater than I ever imagined," study lead Thomas Watters, a geologist and scientist emeritus at the Smithsonian’s Center for Earth and Planetary Studies, said in a statement reported by space.com. "As the interior of the Moon continues to cool and contract, it is expected that the growth of existing faults and formation of new faults continues today."
How it came about
The Moon formed roughly 4.5 billion years ago after a massive collision with the early Earth. Its interior has been cooling ever since, a process that drives the gradual contraction observed today. By mapping the newly identified faults, researchers are piecing together a timeline of lunar tectonic activity that may inform future mission planning, especially for landers and rovers that must navigate a surface marked by these structural features.
Key facts
- The Moon’s radius has shrunk by about 148 feet (45 meters) over the past 400‑800 million years. (space.com)
- Researchers identified more than 10,000 young faults using LROC images. (space.com)
- Faults include over 8,900 lobate scarps and more than 2,000 small mare ridges. (space.com)
- Thomas Watters leads the study and is a scientist emeritus at the Smithsonian’s Center for Earth and Planetary Studies. (space.com)
Sources
- [1] space.com — originally reported as “The moon is shrinking. 10,000 cracks on the lunar surface reveal by how much”
