The Moon has revealed the trace of an event no one saw happen. By comparing maps captured at different times by the Lunar Reconnaissance Orbiter, a scientist discovered a crater 222 meters wide and 43 meters deep that formed in spring 2024. Named McGetchin, it is the largest newly formed crater identified in the solar system and provides an unexpected laboratory for preparing a sustained human presence on the lunar surface.
The responsible object, a fragment of an asteroid or comet, may have been the size of a three- to six-story building. It struck the Moon’s eastern visible edge between April 11 and May 22, 2024. No telescope on Earth or in space detected the collision in real time. The landscape changed in silence, and the evidence then remained hidden inside a vast volume of orbital data.
A discovery born from a routine check
Robert Wagner, an image-processing specialist working with LRO camera data, was performing a quality check when he noticed a bright area surrounded by a dark halo. Software had stacked hundreds of old and recent images: unchanged elements appeared gray, while differences became bright or dark. The debris pattern was so large that it looked nothing like ordinary alerts.
The first identification occurred on October 24, 2025. More precise images captured by the narrow-angle camera during later passes revealed the crater’s shape and the extent of the affected terrain. Several teams then confirmed and studied the discovery before two papers appeared in Science Advances.
A statistically exceptional impact
Researchers estimate that an impact of this magnitude occurs roughly once a century, perhaps less often. McGetchin spans the equivalent of two football fields and is far larger than the new craters LRO usually finds. It is about three times bigger than the previous recent record holder discovered by the spacecraft.
The Moon is nevertheless struck constantly. With no atmosphere to slow or burn them up, rocks and dust reach the ground directly. Since its mission began in 2009, LRO has helped identify at least one thousand new craters and roughly one hundred thousand other surface changes. Impacts producing holes tens of meters wide are much more common than collisions comparable to McGetchin.
The effects extend far beyond the hole
The crater is only the visible center of a much wider transformation. Material was thrown across more than 100 kilometers around the impact point. The debris appears to have traveled at higher angles than expected, an important clue for understanding how far a local event could threaten distant equipment.
The Diviner thermal instrument also detected a cold region seven kilometers wide around the crater. During lunar night, that area is about nine degrees Celsius cooler than neighboring terrain. The impact loosened the regolith, reducing its density and its ability to retain heat. This change, invisible in ordinary light, shows that collisions alter soil properties far beyond their rims.
A lesson for wheels and habitats
For robotic exploration, recently disturbed ground can change wheel grip and sinkage. For a human base, fast-moving ejecta raises another question: how much resistance should be designed into habitats, solar panels, antennas and vehicles? Scientists now want to calculate the likelihood that fragments thrown from future craters could reach planned installation zones.
This is not a reason to abandon lunar projects because of a once-in-a-century event. Space engineering works by turning rare phenomena into measurable requirements. Understanding fragment size, speed, launch angle and travel distance allows designers to select appropriate materials, shielding and safety margins.
The lunar surface is less still than it looks
Ancient craters give the Moon a frozen appearance, but McGetchin is a reminder that the landscape keeps evolving. Estimates drawn from LRO observations suggest that the upper two centimeters of soil may be overturned by ejecta in about 80,000 years. On a geological scale, that is fast.
This activity also changes our relationship with human traces. Footprints left by Apollo astronauts are not eternal. They will eventually be erased by the slow gardening of regolith produced by countless impacts. The Moon preserves marks for a long time, but it is neither an immutable museum nor a landscape without geological weather.
The strategic value of orbital archives
The discovery finally demonstrates the value of a long mission. LRO has orbited the Moon for more than seventeen years with seven instruments measuring topography, composition, temperature and radiation. A single image describes a place; an archive spanning many years reveals change. As the time series grows, it becomes better able to separate exceptional events from noise.
McGetchin was not found by a sensor built specifically to wait for a giant impact. It emerged through methodical comparison, detection software and human attention to an anomaly. As scientific and commercial activity around the Moon increases, this combination of permanent monitoring and patient analysis is becoming a safety infrastructure in its own right.