NASA Found a Once-in-a-Century Crater Hiding on the Moon

Sometime between April 11 and May 22, 2024, a piece of the solar system slammed into the Moon. There was no warning siren. No viral telescope clip. No crowd watching a flash in the lunar night. The incoming object—perhaps an asteroid fragment, perhaps part of a comet—crossed the final distance without an atmosphere to slow it, heat it into a protective burn or tear it apart.

In seconds, the collision excavated a steep-sided crater about 728 feet (222 meters) wide and up to 141 feet (43 meters) deep. The hole was broader than Rome’s Colosseum. Material blasted outward in bright rays and churned the lunar surface for more than 66 miles, or 100 kilometers. And for more than a year, nobody realized what had happened.

The impact was sitting inside the archive of NASA’s Lunar Reconnaissance Orbiter, a spacecraft that has been circling the Moon since 2009. It emerged not from a dramatic alert but from a routine data-quality check. On October 24, 2025, image-processing specialist Robert Wagner was comparing global lunar maps when he noticed an enormous bright mark wrapped in a dark halo.

The mark turned out to be ejecta surrounding the largest newly formed crater ever identified in the solar system—not the solar system’s largest crater, but the largest one whose recent formation scientists have documented.

NASA announced the discovery on September 16, 2026, alongside two papers in Science Advances. The crater has been named McGetchin, honoring the late lunar scientist Thomas McGetchin.

The headline is a cosmic jump scare: an object possibly as large as a three- to six-story building struck our nearest neighbor and escaped real-time detection.

The science is even more consequential. The collision left behind a natural experiment that could change how engineers think about lunar bases, rover routes, buried resources—and the supposedly permanent footprints of the Apollo astronauts.

1. A New Crater Was Hiding in Plain Sight

The 2024 impact excavated a 222-meter hole, chilled a seven-kilometer patch of lunar ground and scattered debris across more than 100 kilometers. Scientists found it only later, hiding in orbital data.

The wide-angle camera had imaged the changed landscape in May 2024, soon after the impact. But no automated alarm announced that a new crater had formed. The event was not confirmed by telescopes watching for impact flashes from Earth or space. Its signature waited in pixels until Wagner built global “before” and “after” mosaics and used software to highlight changes.

Most candidate changes were not craters. Small shifts in lighting, viewing angle and shadow generated false alarms. New impacts usually appeared as tiny fuzzy halos around points only a pixel wide. McGetchin was different: its debris pattern sprawled across hundreds of pixels.

Once the team knew where to look, sharper narrow-angle images revealed the crater itself. A December 5, 2025, pass resolved its size and shape at roughly three feet per pixel. Additional images and thermal measurements turned one bright anomaly into a detailed reconstruction.

This was not an impact witnessed live. It was a crime scene discovered after the fact, with an orbiter supplying the security-camera footage.

2. Bigger Than The Colosseum

The crater was about 728 feet (222 meters) wide and up to 141 feet (43 meters) deep. The hole was broader than Rome’s Colosseum. Material blasted outward in bright rays and churned the lunar surface for more than 66 miles, or 100 kilometers.

McGetchin is described by NASA and the research team as the largest newly formed impact crater ever discovered in the solar system. That does not mean no larger crater has formed in recent history. It means no larger new crater has been identified through comparable before-and-after observations.

Nor is McGetchin remotely close to the largest crater on the Moon. Ancient basins span hundreds or thousands of kilometers. The South Pole–Aitken basin is about 2,400 kilometers across. McGetchin is remarkable because scientists can constrain its formation to a six-week window in 2024 and compare the landscape before and after.

3. The Moon Has a 7-Kilometer Cold Scar

NASA’s Diviner instrument measures thermal radiation from the lunar surface. When researchers examined the impact site, they found a cold region approximately four miles, or seven kilometers, wide. At night, it was about 16°F, or 9°C, cooler than the surrounding terrain.

The Moon’s loose surface layer is called regolith—a mixture of dust, broken rock and glass produced by billions of years of impacts. Dense or rocky material stores and releases heat differently from fine, loosely packed particles. When McGetchin formed, the shock and ejecta “fluffed up” or decompacted the surrounding regolith.

Loose material has more pore space and poorer thermal conductivity. It does not retain daytime heat as efficiently, so it cools faster during the lunar night. From orbit, the changed soil appears as a thermal cold spot far wider than the crater.

This makes temperature a geological detective tool. A fresh impact may leave a subtle thermal signature long after its bright visual rays become harder to interpret. By measuring how cold spots evolve, scientists can investigate how quickly regolith settles, mixes and ages.

The large size of the McGetchin anomaly also shows that impacts mechanically alter terrain well beyond obvious excavation. A rover might encounter different bearing strength, wheel sinkage or traction even outside the visible crater.

4. Could This Happen Near a Moon Base

Small objects frequently hit the Moon. The lunar surface covers almost 38 million square kilometers, while a base or landing zone would occupy a tiny fraction of that area. A McGetchin-scale event occurring somewhere on the Moon once per century does not translate into a once-per-century strike on a base.

Direct impact would be extraordinarily unlikely for a small settlement. Ejecta expands the hazard radius, but the probability still depends on where the impact occurs and how debris travels.

The new observations give mission planners evidence rather than reassurance by intuition. They can estimate distributions of fragment size and velocity, model damage thresholds, and decide whether critical systems need redundancy or shielding. Habitats may be covered with regolith not only for radiation protection but also to absorb small high-speed projectiles. Equipment could be spaced so one event cannot disable an entire outpost.

McGetchin also offers opportunity. Fresh craters expose material normally buried below the surface. That can provide access to less weathered rocks, subsurface ice or geological layers without drilling as deeply. Future robotic missions could study fresh ejecta to learn about lunar history and resource distribution.

5. The Moon Is Not a Dead World

The phrase “dead world” usually means geologically inactive: no rain, oceans, plants or plate tectonics continually reshaping the surface. But the Moon is not frozen in time.

LRO researchers have identified at least 1,000 new impact craters and flagged roughly 100,000 other surface changes associated with impacts and flying debris. Objects large enough to make craters around 30 feet wide may do so approximately 140 times across the Moon each year. Microscopic projectiles strike vastly more often.

Each collision gardens the regolith. It excavates buried grains, covers exposed material, breaks rocks and mixes surface layers. Over long timescales, countless small impacts can transform more ground than rare dramatic events.

The McGetchin studies support an estimate that ejecta overturns the upper inch or roughly two centimeters of lunar soil on a timescale of about 80,000 years.

6. We Didn’t See The Impact, We Saw Its Evidence

This was not an impact witnessed live. It was a crime scene discovered after the fact, with an orbiter supplying the security-camera footage.

The impact was sitting inside the archive of NASA’s Lunar Reconnaissance Orbiter, a spacecraft that has been circling the Moon since 2009. It emerged not from a dramatic alert but from a routine data-quality check. On October 24, 2025, image-processing specialist Robert Wagner was comparing global lunar maps when he noticed an enormous bright mark wrapped in a dark halo.

The mark turned out to be ejecta surrounding the largest newly formed crater ever identified in the solar system—not the solar system’s largest crater, but the largest one whose recent formation scientists have documented.

The wide-angle camera had imaged the changed landscape in May 2024, soon after the impact. But no automated alarm announced that a new crater had formed. The event was not confirmed by telescopes watching for impact flashes from Earth or space. Its signature waited in pixels until Wagner built global “before” and “after” mosaics and used software to highlight changes.

Once the team knew where to look, sharper narrow-angle images revealed the crater itself. A December 5, 2025, pass resolved its size and shape at roughly three feet per pixel. Additional images and thermal measurements turned one bright anomaly into a detailed reconstruction.