In the quiet discipline of routine data review, a NASA scientist encountered something the Moon had not shown before — a fresh wound on an ancient face. Between April and May of 2024, a space rock several stories tall struck the lunar surface, carving a crater nearly 728 feet wide in an event scientists estimate occurs only once a century. Named McGetchin in honor of a pioneering lunar researcher, the crater is more than a geological curiosity; it is a reminder that the Moon, long imagined as frozen in time, is still being written upon by the cosmos.
NASA scientist's routine check uncovers rare lunar crater formed by once-in-century impact
A bright spot stopped him cold, and everything changed
Mark
So Wagner wasn't looking for a crater at all—he was just checking data quality. That's a pretty mundane task to stumble onto something this rare.
Mimi
Exactly. He was doing the kind of work that keeps missions running, not the kind that usually makes discoveries. But he noticed something that didn't fit the pattern, and he had the instinct to stop and investigate.
Luke
How confident are we that this is actually a once-in-a-century event? The source says scientists estimate that, but who's doing the estimating, and what's that based on?
Mimi
That's a fair question. They're extrapolating from the frequency of detectable impacts over the years of LRO observations. They see about 140 craters of detectable size form each year, and McGetchin is much larger than that.
Mark
And the crater itself—728 feet wide, 141 feet deep—those are precise measurements. How do they get those numbers from orbital images?
Mimi
LRO has instruments that can measure topography and surface elevation. They're not guessing; they're using actual data from the spacecraft's sensors.
Luke
But here's what I want to know: they say the impact happened between April 11 and May 22, 2024. That's a six-week window. Why can't they narrow it down further?
Mimi
Because that's the gap between the last image showing no crater and the first image showing the crater. Without continuous monitoring, that's the best precision you get.
Mark
The cold spot around the crater—four miles wide, 16 degrees cooler at night. That seems like it could matter for future missions.
Mimi
It does. It tells us that impacts don't just make a hole; they change the physical properties of the surface for miles around. That affects how rovers move, how instruments read temperature, everything.
Luke
But we don't know yet what the long-term implications are, right? This is one crater. We're still learning what it means.
Mimi
True. But that's exactly why long-term monitoring like LRO's matters. One crater is data. A century of observations is understanding.
Le Pouls
- A routine image-quality check became extraordinary when scientist Robert Wagner spotted a bright anomaly ringed by darkness on the Moon's eastern edge — something that simply had not been there before.
- The impact, estimated to have struck between April and May 2024, was caused by a space rock three to six stories tall, powerful enough to gouge a cavity deep enough to swallow three school buses stacked vertically.
- Follow-up thermal observations revealed a cold zone stretching four miles beyond the visible crater — far wider than expected — signaling that lunar impacts reshape terrain in ways that extend well past what the eye can see.
- The discovery depends entirely on 17 years of continuous lunar monitoring by the Lunar Reconnaissance Orbiter, without which the new crater would have been indistinguishable from the Moon's ancient, cratered past.
In the quiet discipline of routine data review, a NASA scientist encountered something the Moon had not shown before — a fresh wound on an ancient face. Between April and May of 2024, a space rock several stories tall struck the lunar surface, carving a crater nearly 728 feet wide in an event scientists estimate occurs only once a century. Named McGetchin in honor of a pioneering lunar researcher, the crater is more than a geological curiosity; it is a reminder that the Moon, long imagined as frozen in time, is still being written upon by the cosmos.
Robert Wagner was performing a data-quality check on lunar imagery — the unglamorous work that keeps scientific missions alive — when a bright spot ringed by a dark halo on the Moon's eastern edge brought him to a full stop. Comparing images taken at different times confirmed what he suspected: the mark had not existed before. Sometime between April 11 and May 22, 2024, a space rock roughly the height of a three- to six-story building had struck the Moon, carving out what is now called McGetchin crater — 728 feet wide, 141 feet deep, and named in honor of pioneering lunar scientist Tom McGetchin.
An impact of this scale is estimated to occur on the Moon only once per century, sometimes less frequently. The Moon's lack of atmosphere leaves it entirely exposed to the cosmos — every asteroid and comet fragment arrives at full speed, with nothing to slow or burn it away. NASA's Lunar Reconnaissance Orbiter, circling the Moon for more than 17 years, has catalogued over 1,000 new craters and roughly 100,000 other surface changes in that time, but McGetchin stands apart for its sheer scale and rarity.
What deepened the discovery was what thermal instruments found afterward: a zone nearly four miles wide surrounding the crater running about 16 degrees Fahrenheit cooler at night than the surrounding terrain. The impact had disturbed the surface far beyond its visible edge — exposing subsurface rock, altering how sunlight interacts with the ground, and creating conditions that could affect future lunar missions in practical ways, from rover traction to instrument calibration.
Wagner's find is ultimately a testament to the value of sustained, patient observation. Without nearly two decades of overlapping images of the same terrain, the crater would have been just another ancient scar. Instead, it became proof of an ongoing process — evidence that the Moon, so often imagined as still and unchanging, continues to be shaped by the same violent forces that have sculpted planetary bodies since the solar system's earliest days.
Robert Wagner was doing the kind of work that rarely makes headlines—a data-quality check on lunar imagery, the sort of routine task that keeps scientific missions running smoothly. He was staring at a massive map of the Moon when something stopped him cold. A bright spot, ringed by a darker halo, sat on the eastern edge of the lunar surface. "I just stopped, dropped everything, and started looking into what that spot was," Wagner, an image-processing specialist working with NASA's Lunar Reconnaissance Orbiter Camera, would later recall. What he found was McGetchin crater, a freshly formed impact scar that scientists now understand represents one of the rarest events visible from space—a collision powerful enough to reshape the Moon's surface in a way we can actually see.
The crater's existence became clear only when Wagner compared images taken at different times. The spot had not been there before. Somewhere between April 11 and May 22, 2024, a space rock roughly the size of a three- to six-story building had slammed into the Moon's surface. The impact carved out a crater 728 feet across and 141 feet deep—picture two football fields laid end to end, with a cavity deep enough to swallow three school buses stacked vertically. Scientists estimate that an impact of this magnitude happens on the Moon roughly once every century, sometimes longer. The crater was officially named McGetchin, honoring Tom McGetchin, a pioneering lunar scientist.
What makes this discovery particularly striking is not just the crater itself, but what it reveals about how the Moon continues to change. The Lunar Reconnaissance Orbiter, which has been circling the Moon for more than 17 years, carries seven instruments designed to map and monitor the lunar environment. Over that span, scientists have identified at least 1,000 new impact craters and catalogued roughly 100,000 other surface changes caused by impacts or debris ejected during collisions. The smallest craters visible in LRO images are about 30 feet wide, created by rocks the size of a monster-truck tire. Scientists calculate that impacts producing craters of detectable size occur around 140 times each year across the Moon. But most new impacts are far smaller, leaving marks too tiny to resolve from orbit.
The Moon's vulnerability to these collisions stems from a simple fact of planetary physics: it has no atmosphere. Earth's thick blanket of air slows incoming space rocks and burns up the smaller ones before they reach the ground. The Moon sits naked to the cosmos, exposed to every asteroid and comet fragment drifting through space. What arrives at the lunar surface arrives at full speed, with full force.
Wagner's discovery triggered a broader investigation. Scientists working with LRO's thermal instrument, called Diviner, conducted follow-up observations of the McGetchin site and found something unexpected: a zone roughly four miles wide surrounding the crater that runs about 16 degrees Fahrenheit cooler at night than the surrounding terrain. The extent of this cold spot surprised researchers because it demonstrated that impacts reshape the Moon far beyond the visible crater itself. The disturbance of surface material, the exposure of subsurface rock, and the changes to how sunlight interacts with the ground all ripple outward in ways that thermal instruments can detect. These physical alterations could affect how rover wheels grip the surface, how instruments measure temperature, and how future missions navigate the lunar landscape.
The discovery underscores why long-term monitoring matters. A feature that appeared unexpectedly during a routine data check might have gone unnoticed without years of overlapping observations covering the same terrain. Wagner's moment of attention—stopping mid-task to investigate an anomaly—only yielded its full significance because the Lunar Reconnaissance Orbiter had been watching the same patch of Moon for nearly two decades. The before-and-after images provided the proof that something genuinely new had occurred. In the absence of that historical record, the crater would have been just another mark on an ancient, cratered world. Instead, it became evidence of an ongoing process, a reminder that even the seemingly static Moon is still being shaped by the violent collisions that have defined planetary bodies since the solar system's birth.
Citations marquantes
I just stopped, dropped everything, and started looking into what that spot was— Robert Wagner, NASA scientist
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