A fresh 222-meter lunar crater gives impact modelers a sample of one
McGetchin is the freshest large crater on the Moon's record. Its value to cratering science is that it is unweathered. The once-per-130-years recurrence figure still comes from a size model.
The Scientist · Science desk
What happened
- Two papers published Sept. 16 in Science Advances describe the freshest large impact crater yet found on the Moon, named McGetchin for the late lunar geologist Tom McGetchin.
- The impact happened in April or May 2024, and a colleague of the camera team found the resulting crater in Lunar Reconnaissance Orbiter data in October 2025.
- The team estimates the impactor was the size of a three-to-six-story building, and it struck where the dark volcanic mare meets the brighter ancient highlands.
- The orbiter circles the Moon about 12 times a day and images only a small strip per pass. Without a flash to aim at, the hunt for new craters is essentially random.
Why it matters
- What's now possible capability Excavation and ejecta models can be tested against a crater shape weathering has not touched. No terrestrial impact structure offers that.
- What it limits constraint Any craters-per-year figure built from orbiter detections is a floor, because repeat coverage of the same ground takes years and new holes turn up by luck.
- What it sets up precedent Stopar's appeal for amateur footage puts sky-watching archives in play as dating evidence for the next large impact someone finds late.
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On Earth, weathering and degradation strip most of the original detail out of an impact structure; the Moon keeps it [11]. A crater about 2.5 years old keeps all of it, and Julie Stopar said this one is "in really, really good condition" [10]. Divide its 43-meter depth by its 222-meter width [3] and the shape comes out at about 0.19 [14], a ratio that stands as measured, with no erosion or infill correction to apply.
The landing site adds something. The object came down on the boundary between the dark volcanic mare plains and the brighter, hillier highlands, which are ancient crustal material, and the excavated material reflects both units [19]. For scale, the South Pole-Aitken basin is roughly 10,000 times wider [17], about 2,200 kilometers [20]. McGetchin is a small crater by lunar standards; it is the largest new one in the orbiter's 17 years of imaging [8].
The recurrence figure comes from the impactor population. "We know generally that there's more small things in space than there are large things, so that means we tend to get a lot of small craters on the moon and very few large craters," Stopar, deputy principal investigator on the orbiter's camera team, told Live Science [5][7]. Set the 130-year interval against LRO's 17 years of operation and the expected number of craters this size in the mission so far is 0.13 [16]. One detection sits comfortably with that. It does not tighten the estimate, and Live Science did not report an uncertainty on the 130-year figure.
The detection history is worth holding onto for the next one. LRO has taken more than 3 million images since 2009, and the two papers published Sept. 16 in Science Advances draw on a few hundred of them [13][4]. Between the April or May 2024 impact and the October 2025 identification, about 17 months passed [15].
There may also be a recording. Stopar said flashes from smaller impacts have been seen from Earth and that this one may have made one under good conditions [23]. "We don't know if anyone was watching, though," she said, and added that "if somebody out there has videos that they can dig through, they could go back and look for it" [24][25]. Amateur observers have since reported picking out the crater's bright debris ring from Earth [22]. A timestamped flash would replace a two-month formation window [18] with a moment.
What to watch
- Whether any amateur or observatory video from April or May 2024 contains an impact flash that fixes the formation time.
- Whether more new craters turn up as the team works further into the orbiter's archive of more than 3 million images.
- Whether reports of the bright debris ring seen from Earth hold up under larger telescopes.
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- Hype gap+22
- Incentives38
- Confidence68
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- [1]
Scientists studying a few hundred of the orbiter's photos announced what they are calling a once-in-a-century discovery: the biggest, freshest impact crater ever seen in the solar system, made by a building-size meteorite two years ago.
- [2]
The crater is named McGetchin, after the late geologist and lunar scientist Tom McGetchin.
- [3]
McGetchin crater is about 222 meters (728 feet) wide on average and 43 meters (141 feet) deep.
- [4]
The team described its findings in two papers published Sept. 16 in the journal Science Advances.
- [5]
"We know generally that there's more small things in space than there are large things, so that means we tend to get a lot of small craters on the moon and very few large craters," Julie Stopar told Live Science.
- [6]
Stopar said: "So something the size of this crater, we only expect to encounter that once every 130 years, approximately."
- [7]
Julie Stopar is a senior staff scientist at the Lunar and Planetary Institute and deputy principal investigator on the Lunar Reconnaissance Orbiter's camera team, which discovered McGetchin crater.
- [8]
McGetchin appeared seemingly out of nowhere in images from spring 2024 and is the biggest new crater scientists have seen in the 17 years the Lunar Reconnaissance Orbiter has been active.
- [9]
The impact happened in April or May 2024, and one of Stopar's colleagues discovered the crater in Lunar Reconnaissance Orbiter data in October 2025.
- [10]
Stopar said the crater is only about 2.5 years old and is "in really, really good condition", not yet weathered.
- [11]
Stopar said that on Earth a lot of the original detail of impact craters is lost through weathering, degradation and time, while the Moon preserves it much better.
- [12]
By the team's estimates, the meteorite that made the crater was the size of a three-to-six-story building.
- [13]
NASA's Lunar Reconnaissance Orbiter, a robotic satellite about the size of a minivan, has taken more than 3 million photos of the lunar surface since launching in 2009.
- [14]
McGetchin's depth-to-diameter ratio is about 0.19.
- [15]
About 17 months separated the April or May 2024 impact from the crater's identification in orbiter data in October 2025.
- [16]
At one crater this size every 130 years, the expected number formed during the orbiter's 17 years of operation is about 0.13.
- [17]
The Moon's largest crater is the South Pole-Aitken basin, about 10,000 times wider than the newly discovered crater.
- [18]
The impact time is currently constrained to a window of about two months.
- [19]
The impact occurred on the boundary between the dark, flat volcanic mare deposits and the brighter, hillier highlands of ancient crustal material, and that boundary is reflected in the materials excavated by the crater.
- [20]
The South Pole-Aitken basin is therefore roughly 2,200 kilometers across.
- [21]
Stopar said the orbiter circles the Moon about 12 times each day and can image only a small portion of the surface on each pass, so without an impact flash to indicate where to look the search for new craters is basically random, and repeat imaging of a given area takes years.
- [22]
Some skywatchers think they have spotted the crater's bright, white debris ring from Earth.
- [23]
Stopar said flashes associated with smaller impacts have been observed from Earth and that it is possible, under good conditions, that this impact made a flash.
- [24]
Stopar said: "We don't know if anyone was watching, though".
- [25]
Stopar said: "if somebody out there has videos that they can dig through, they could go back and look for it".
Sources
3 independent publishers whose own reporting we read for this story.
- livescience.com'We only expect to encounter that once every 130 years': A huge new crater on the moon could mean a giant leap for lunar science, veteran researcher says
1 article · September 22, 2026
- nasa.govAPOD: 2026 September 23 – A New Lunar Crater: McGetchin
1 article · September 22, 2026
- scientificamerican.comScientists discover largest new impact crater in the solar system ever—on our moon
1 article · September 22, 2026
Topics and entities
Topics
- Impact Cratering
- Lunar Exploration
- Orbital Remote Sensing
Entities
- Lunar Reconnaissance Orbiter
- Lunar and Planetary Institute
- Intuitive Machines
- South Pole-Aitken basin
- NASA
- Science Advances
- McGetchin crater