On October 24, 2025, Robert Wagner was doing what he’d done countless times before — scanning composite maps of the Moon for subtle changes in the lunar surface. Then he stopped.
On his screen, an unusually bright patch surrounded by a dark halo had appeared where none existed before. Wagner, an image-processing specialist working with NASA’s Lunar Reconnaissance Orbiter Camera, set aside everything else and started digging.
What he’d stumbled onto, buried in a routine global comparison of before-and-after images, was anything but routine.
A routine scan that stopped a scientist cold
Wagner wasn’t hunting for anything extraordinary. His task was a periodic, wide-scale comparison of lunar maps — a search for features wider than 150 feet that the team runs every few years. To do it, he stacked hundreds of “before” and “after” images using software designed to flag differences. Areas that hadn’t changed appeared gray. Anything that had shifted showed up as a bright or dark patch.
The method works, but it’s slow going. Even minor shifts in shadow or lighting can fool the software, generating hundreds of false signals. Wagner’s usual routine meant searching for tiny, fuzzy halos around single-pixel bright points — subtle hints of regolith sprayed outward by a small, fresh impact.
McGetchin was nothing like that.
The debris pattern stretched across hundreds of pixels and dominated the image. “It was by far the most obvious impact debris pattern I’ve ever seen in one of these images,” Wagner said. He pulled up older and newer LRO images of the same region, comparing them side by side until the picture became clear: a massive crater had appeared where none had existed before.
McGetchin: a crater that broke the record
The crater was officially named McGetchin, honoring pioneering lunar scientist Tom McGetchin. It sits near the Moon’s eastern edge and formed sometime between April 11 and May 22, 2024 — the window between two LRO imaging passes that bracketed its appearance.
The numbers are striking. McGetchin measures 728 feet wide, roughly the length of two football fields, and plunges 141 feet deep — enough vertical space to stack three school buses on top of one another. An asteroid or comet approximately the size of a three- to six-story building carved it out in an instant. On September 16, researchers published their findings in Science Advances, confirming McGetchin as the largest newly formed impact crater ever identified anywhere in the solar system. Scientists estimate that an impact of this scale may happen on the Moon only about once per century, or even less frequently.
Why the Moon bears every scar
Earth gets hit too, but its thick atmosphere burns up or slows most incoming rocks before they reach the ground. The Moon has no such protection. Whatever strikes heads straight for the surface.
LRO has been orbiting the Moon for over 17 years, and in that time researchers have catalogued at least 1,000 new impact craters, along with roughly 100,000 additional surface changes caused by direct strikes or by debris thrown outward during nearby impacts. Most of those craters are tiny — the smallest LRO can reliably detect run about 30 feet across, produced by rocks roughly 43 inches wide, about the size of a monster-truck tire. Scientists estimate that impacts large enough to leave detectable craters happen approximately 140 times per year across the entire lunar surface. McGetchin is in a category of its own.
A cold zone four miles wide — and what it means
Spotting the crater was only the beginning. After Wagner’s initial discovery, scientists turned LRO’s thermal instrument, Diviner, toward the site. What they found surprised them.
A zone roughly four miles wide surrounding McGetchin runs about 16°F colder at night than the terrain around it — a substantial temperature difference extending well beyond the crater’s visible rim. The explanation lies in what the impact did to the lunar regolith. The collision churned and loosened the surrounding material, leaving it less dense. Less-dense regolith holds heat less efficiently, so it cools faster after sunset, producing the broad cold signature Diviner detected.
The scale of the disturbance was unexpected. It shows that a single impact can reshape the lunar surface well beyond the crater itself, in ways a camera alone can’t capture. Differences in regolith density and texture can also affect how rover wheels grip and move — a real engineering concern as NASA plans future crewed and robotic missions.
What this means for the future of lunar exploration
McGetchin’s discovery is, in part, a story about patience. LRO has been quietly circling the Moon for nearly two decades, building a baseline of observations detailed enough to catch a change like this. Without that long-running record, the crater might have gone unnoticed for years.
The LROC imaging system — combining wide-angle global maps with narrow-angle close-ups at roughly three feet per pixel — proved essential both to finding McGetchin and to characterizing it precisely. More detailed results on the size and energy of the impacting object are still forthcoming.
The broader lesson matters as NASA works toward sustained human presence on the Moon. The surface isn’t static. Craters form, regolith shifts, and a landscape that looks unchanged today may look different next year. McGetchin is a reminder that lunar planning has to account for a world that keeps changing — and that the tools to track those changes are already in orbit, watching.
If you want to learn more about this discovery, check the complete study here: Mark S. Robinson, Aaron K. Boyd, Prasun Mahanti, Madeleine R. Manheim, Emerson J. Speyerer, Julie D. Stopar, Robert V. Wagner. A new 222-m diameter lunar crater. Science Advances, 2026; 12 (38) DOI: 10.1126/sciadv.aeh7812
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