NASA Orbiter Spots McGetchin, the Largest Fresh Impact Crater Ever Found in the Solar System

NASA's Lunar Reconnaissance Orbiter (LRO) has circled the Moon for more than 17 years, carrying seven instruments and returning a continuous record of a surface that most people assume barely changes. On October 24, 2025, that assumption took a hard correction during what was supposed to be a routine data-quality check.

Robert Wagner, an image-processing specialist from Intuitive Machines who works with data from the Lunar Reconnaissance Orbiter Camera team, was scanning a giant Moon map built by stacking hundreds of before-and-after LROC Wide-Angle Camera frames. He saw an unusually large bright spot circled by a dark halo, compared the before and after views, and realized he had found the largest newly formed crater ever detected in the solar system.

The crater, now officially named McGetchin, formed on the Moon's eastern edge between April 11 and May 22, 2024, when a comet or asteroid the size of a three- to six-storey building struck the surface. It measures 728 feet (222 meters) wide, roughly the length of two American football fields, and 141 feet (43 meters) deep, enough to fit three vertically stacked yellow school buses.

The discovery was reported in a pair of papers in Science Advances on September 16, 2026. Mark Robinson, principal investigator for the LRO camera team and chief scientist for the cameras at Intuitive Machines, is lead author of one study. The other was led by David Paige of the University of California, Los Angeles, with Julie Stopar of the Universities Space Research Association's Lunar and Planetary Institute as a co-author. Scientists estimate that an impact of this magnitude happens on the Moon about once in a century or longer.

Key Facts

NASA Science reported on September 16, 2026, that the impact escaped real-time detection by telescopes on Earth and in space, and that LRO's wide-angle images went unidentified in the flood of data until August 2025. The spacecraft then gathered more detailed pictures in the fall of 2025, and the discovery was confirmed early in 2026. The crater is named for the late Thomas McGetchin, a pioneering lunar scientist.

The Associated Press reported on September 16, 2026, that the steep-sided hole is the solar system's biggest known impact crater carved out in recent times and that such a large-scale event is estimated to occur only once every 132 years. The new crater is three times bigger than the previous record-holder found by LRO a decade ago. It is larger than the Roman Colosseum, and this latest impact churned the lunar surface for more than 66 miles (100 kilometers).

The Universities Space Research Association said in its September 16, 2026 release that McGetchin served as director of the Lunar and Planetary Institute, then known as the Lunar Science Institute, beginning in 1977, the same year that marked the inaugural summer of the institute's Internships in Planetary Science Program. A renowned volcanologist and lunar scientist, McGetchin developed a model of impact-crater ejecta in 1973 with colleagues that remains an important framework for interpreting the formation and distribution of material thrown from impact craters and basins. The crater sits on a boundary between the cratered, craggy lunar highlands and a wide, flat mare, and a bright blanket of ejecta extends hundreds of meters from its rim.

Follow-up thermal observations with LRO's Diviner instrument between November 15, 2025 and February 18, 2026 found a 4-mile-wide (7 kilometer wide) area around the crater that is about 16 degrees Fahrenheit cooler at night than its surroundings, consistent with a loosening of the Moon's top soil. LROC images are collected from about 60 miles above the Moon, and the Narrow-Angle Camera takes views at about 3 feet per pixel. The smallest craters distinguishable in LRO images are about 30 feet wide, made by rocks about 43 inches wide, and impacts of that scale produce about 140 new craters across the Moon each year.

The full author list for the first Science Advances paper includes Mark S. Robinson, Aaron K. Boyd, Prasun Mahanti, Madeleine R. Manheim, Emerson J. Speyerer, Julie D. Stopar and Robert V. Wagner. The two studies carry the titles 'A new 222-m diameter lunar crater' and 'New lunar crater reveals extensive distal regolith modification,' and both appear in the journal on September 16, 2026.

Analysis

What this really means is that the Moon is a far more active world than its grey, airless reputation suggests, and that the instrument best suited to measuring that activity has spent nearly two decades quietly building the evidence. For more than 17 years LRO has circled the Moon with seven instruments, and the team has identified at least 1,000 new impact craters while flagging 100,000 more surface changes. A single lucky observation becomes credible only because that baseline exists to check it against.

NBC News reported on September 16, 2026, that the impact lofted dust and rocky soil at a higher angle than expected, a detail that matters because ejecta models feed directly into engineering assumptions about how far debris travels and where it lands. Robinson also found that LRO crater discoveries since the 2009 launch show the Moon's top inch (2 centimeters) of soil is overturned by ejected material every 80,000 years, a resurfacing rate faster than previously thought.

Paige, the UCLA co-author, likens the process to gardening. In his framing, impacts churn the sediments and put material above that usually sits below the surface. The 4-mile-wide cold spot is the physical signature of that churn, because fluffed regolith is less dense and stores heat differently, and Diviner can measure the difference from orbit without ever touching the ground.

The bigger picture here is that planetary science has shifted from cataloguing craters to measuring rates, and rates are exactly what engineers need. A crater that formed two years ago, on the near side, and was captured in before-and-after frames is a calibration point that no museum sample or Apollo-era photograph could ever provide.

Why It Matters

The practical stakes are tied to NASA's plan to build a base for astronauts on the Moon. The next step identified by the researchers is to calculate the risk of ejected crater material striking that base. Robinson said the information will help engineers harden structures so that they will not have to worry about damage, or at least worry less.

The result also undercuts a durable piece of lunar folklore. Contrary to the popular belief that the Apollo moonwalkers' dusty footprints will last forever, Robinson said they will definitely be long gone within the 80,000 year resurfacing timeframe. Nothing on the lunar surface is permanent on human timescales, only on geological ones.

The observation is statistically rare in a way that cannot be scheduled. The scientists wrote in one of the two studies that the event constitutes a statistically rare, effectively once-in-a-lifetime observation. Roughly once every 132 years is not a cadence that a mission planner can rely on, which is why the find is valuable precisely because it happened while LRO was watching and had a prior map to compare it with.

Next Up

Researchers will keep mining the McGetchin data while the crater is still fresh. The crater shows the immediate effects of the impact cratering process before exposure to space and meteorite bombardment wears it down, which is what makes it useful for further studies. Because the strike occurred on the Moon's near side and was captured in before-and-after frames, the team holds an unusually complete record of what changed and how quickly.

The risk assessment for the future lunar base is the near-term deliverable, and LRO's long archive will keep supplying the underlying statistics. With seven instruments, more than 17 years of observations, at least 1,000 confirmed new craters and 100,000 flagged surface changes, the orbiter has turned the Moon into a monitored environment rather than a static backdrop.