NASA's Lunar Reconnaissance Orbiter (LRO) has identified the largest newly formed impact crater ever discovered in the solar system, a 222-meter-wide feature named McGetchin that appeared on the Moon in 2024. The discovery, made by chance nearly a year after the impact, offers scientists a rare opportunity to study a large crater with detailed before-and-after images.
The crater formed between April 11 and May 22, 2024, when an asteroid or comet fragment roughly the size of a three- to six-story building slammed into the lunar surface. The resulting bowl-shaped depression has an average diameter of 222 meters, a depth of about 43 meters, and a rim that rises some 8 meters above the surrounding terrain. It is the largest fresh crater identified in the solar system to date.
The find was made in October 2025 by Robert Wagner, an image processing specialist with the Lunar Reconnaissance Orbiter Camera (LROC) team. While comparing images of the lunar surface taken at different times near the eastern limb of the Moon, Wagner noticed an unusually bright spot surrounded by a dark halo. Intrigued, he compared the image with earlier ones and confirmed that the crater had not existed before.
LRO has been mapping the Moon from a polar orbit since June 2009. The spacecraft's Diviner radiometer, which detects thermal anomalies, revealed that McGetchin is surrounded by a cold spot — a region 6 to 7 kilometers across that, during the lunar night, registers temperatures 8 to 9 Kelvin lower than the surrounding terrain. The cause is the impact's shock wave, which churned and loosened the surrounding regolith, the mineral material covering the Moon. This increased porosity allows the regolith to dissipate heat more quickly after sunset than denser material nearby. The data demonstrate that a collision's effects can alter the physical characteristics of the terrain at distances many times greater than the size of the resulting crater.
According to NASA, the impact was a very rare event, of the kind that occurs on average only on timescales of a century or more. The object that struck the Moon had not been observed before the collision, though the flash produced during the impact was seen by chance. The new crater has been officially named McGetchin in honor of planetary scientist Thomas McGetchin.
The discovery is valuable to scientists because it provides a large crater with detailed images from both before and after its formation. However, it also underscores the Moon's ongoing bombardment. Over more than 17 years of LRO observations, astronomers have identified at least 1,000 new craters and roughly 100,000 other surface changes linked to impacts or falling ejecta. NASA estimates that about 140 craters large enough to reach a diameter of roughly 10 meters form on the Moon each year. Virtually none of the recent natural lunar craters identified by LRO have been linked to an asteroid observed and tracked before impact.
The McGetchin crater was photographed by LRO in both visible light and through the Diviner radiometer. The high-resolution image was obtained by the LRO's Narrow Angle Camera. The discovery highlights how the lunar surface continues to change slowly, not because of geological activity, but because of the constant rain of asteroids and comet fragments from space.