The moon is shrinking. 10,000 cracks on the lunar surface reveal by how much

Scientists have calculated how much the moon has shrunk over millions of years by studying thousands of surface cracks. The moon is gradually contracting as its interior cools from the ancient collision that formed it about 4.5 billion years ago. In a study published October 14 in The Planetary Science Journal, researchers analyzed images from the Lunar Reconnaissance Orbiter Camera to map more than 10,000 young faults.

Study lead Thomas Watters of the Smithsonian noted that the number of observed faults is much greater than previously imagined. Based on these findings, the team estimates the moon's radius has decreased by about 148 feet over the past 400 to 800 million years. Unlike Earth, which features roughly 15 major tectonic plates, the moon is a single-plate body.

Because its outer shell is one solid piece, cooling and contraction cause faults to appear scattered all over the surface rather than at plate boundaries. The mapped features include lobate scarps, which are long curved structures formed when the surface cracks and pushes upward, and small mare ridges that resemble narrow wrinkles.

Researchers also found that areas with thicker lunar crust have fewer faults, suggesting those regions were initially insulated and resisted early cooling