Scientists have unearthed a crater on the moon that surpasses the size of the Roman Colosseum, resulting from a significant impact two years ago that went unnoticed initially. The crater, with steep sides measuring 222 meters across and up to 43 meters deep, stands as the largest known impact crater in the solar system formed recently.
Considered a rare occurrence, such a large-scale event is projected to happen once every 132 years, presenting a valuable source of information as NASA gears up to establish a base for astronauts on the moon. In one of the two studies published in the journal Science Advances on Wednesday, researchers described the event as a statistically infrequent and virtually once-in-a-lifetime observation.
The Lunar Reconnaissance Orbiter (LRO) operated by NASA identified the crater on the moon’s near side in May 2024 shortly after its creation by a fragment from an asteroid or comet. This lunar impact went undetected in real-time by telescopes on Earth and in space. It wasn’t until August 2025 that LRO’s wide-angle images revealed the crater, with more detailed pictures captured last fall and confirmation of the discovery earlier this year.
Named after the late Thomas McGetchin, a former director of Houston’s Lunar and Planetary Institute, the crater has altered the moon’s surface for over 100 kilometers. Dust and rocky soil were ejected at a higher angle than anticipated, as noted by Mark Robinson, the chief scientist for LRO’s cameras at Intuitive Machines and the lead author of one of the studies.
A separate study unveiled a seven-kilometer-wide cold region surrounding the new crater, indicating a loosening of the moon’s topsoil. Co-author David Paige of the University of California, Los Angeles, likened this phenomenon to gardening, where impacts act to stir the sediments and bring subsurface material to the surface.
Robinson highlighted that LRO’s findings since its inception in 2009 demonstrate that the top two centimeters of the moon’s soil are overturned by ejected material every 80,000 years, a faster process than previously believed. He refuted the common belief that the footprints left by Apollo moonwalkers will endure forever, emphasizing that they will likely vanish within that timeframe.
The next phase involves assessing the risk of ejected crater material striking NASA’s upcoming moon base. This crucial information will guide engineers in fortifying structures to mitigate potential damage concerns.