A 222-Meter Moon Crater Formed Unnoticed—Its Cold Footprint Spans 7 Kilometers
NASA made the finding public on September 16, 2026; its Lunar Reconnaissance Orbiter account places the impact on the Moon’s eastern edge between April 11 and May 22, 2024, and records Robert Wagner’s discovery of the feature in repeat imagery on October 24, 2025. The same observations show that the collision left a crater roughly two American football fields across and a nighttime cold region about 4 miles, or 7 kilometers, wide.
The impact itself escaped real-time detection by telescopes on Earth and in space, according to the Associated Press’s independent coverage, which gives the crater’s width as 222 meters and its maximum depth as 43 meters. That delay is central to the discovery: McGetchin was found by comparing repeated surveys of the lunar surface, not by witnessing the collision.
Repeat maps reduced the impact date to a narrow window
No instrument recorded the moment the incoming asteroid or comet fragment struck. Researchers instead worked backward from observations in which the older terrain remained intact and later coverage containing a new impact signature. The last image without the feature and the first image with it define the formation window.
The Lunar Reconnaissance Orbiter Camera system played two distinct roles. Its Wide-Angle Camera repeatedly surveyed broad portions of the Moon, providing the material for global before-and-after maps. Software aligned and combined those observations so unchanged terrain appeared gray while differences emerged as bright or dark patches.
Illumination changes and moving shadows also create apparent differences, so the automated comparison produces many false alarms. Human review was therefore essential. McGetchin attracted Wagner’s attention as an unusually large bright deposit surrounded by a dark halo—the visible pattern of displaced surface material rather than a plainly resolved cavity.
After the anomaly was recognized, the Narrow-Angle Camera obtained sharper views. Those images resolved the crater’s outline, depth and surrounding ejecta, turning a conspicuous change in a global map into a measurable new landform.
McGetchin is exceptional in the orbiter’s record
The Lunar and Planetary Institute’s September 16 summary identifies McGetchin as the largest crater known to have both formed and been discovered during LRO’s time at the Moon, gives an average depth of about 43 meters and estimates that a crater of its 222-meter diameter forms there only about once every 130 years. It also places the crater near the boundary between rugged lunar highlands and a broad, flatter mare, with a bright ejecta blanket extending hundreds of meters beyond the rim.
The International Astronomical Union named the feature for Thomas McGetchin, a volcanologist, lunar scientist and former director of the Lunar and Planetary Institute. The choice has a scientific connection to the site: McGetchin and his colleagues developed a model used to interpret how ejecta is distributed around impact craters and basins.
A fresh crater of this scale is valuable because its deposits have not yet endured long exposure to micrometeorite bombardment, radiation and repeated heating and cooling. Earlier orbital coverage also gives researchers a known pre-impact surface against which later changes can be measured.
The cold footprint maps disturbance beyond the visible debris
Visible-light observations reveal the cavity, bright excavated material and rays crossing the older terrain. LRO’s Diviner Lunar Radiometer records a different part of the aftermath: after sunset, a much broader region around McGetchin cools more quickly than its surroundings.
The leading explanation is a change in thermal inertia. The collision shook and loosened the upper regolith, leaving it less dense and less able to retain heat through the lunar night. The cold footprint is therefore not another depression or a ring of ice; it is a temperature signature of altered soil structure.
This distinction explains why the thermal anomaly reaches so much farther than the rim. The crater marks the zone of excavation, while the colder region traces subtler shaking and decompaction across ground that may look comparatively ordinary in visible light. Crater diameter alone consequently understates the area physically modified by the impact.
A dated crater can reveal how fresh impacts evolve
McGetchin combines an unusually tight formation window with pre-impact maps, close-up post-impact images and early thermal measurements. Researchers can use that sequence to separate the original effects of the collision from changes caused later by the lunar environment.
Continued observations can show whether the bright ejecta fades, whether the cavity changes and how long the cold anomaly persists. The site may also clarify how impact-driven shaking propagates through shallow regolith—information relevant to interpreting other young craters whose formation times are unknown.
Important details remain unresolved. The public findings do not yet provide a final reconstruction of the incoming object’s dimensions or impact energy, and more detailed estimates are expected from further analysis. What is established is the chronology: an unwitnessed collision altered the surface in spring 2024, repeat imaging exposed the change the following year, and thermal observations revealed a disturbed zone far wider than the visible crater.
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