NASA Scientist's Chance Discovery Reveals Once-in-a-Lifetime Lunar Crater

A routine examination of mapping data by a NASA scientist has led to the accidental discovery of the largest newly formed crater ever detected in the solar system. Robert Wagner initially spotted an unusual bright feature on the lunar surface in 2025 while reviewing data quality reports generated by NASA's Lunar Reconnaissance Orbiter, known as the LRO. Researchers believe the newly identified McGetchin crater was created following a powerful surface impact that occurred just over a year prior to its detection.

Measuring about a kilometre in overall span, the impact site is roughly as wide and about as deep as the Roman Colosseum. Specifically, the crater measures 222 metres across and 43 metres in depth, making it roughly three times larger than the previous record holder discovered by the LRO a decade ago. Scientists describe the event as a rare occurrence that happens only once every 132 years, offering critical insights that researchers hope will inform future lunar investigations.

The LRO has orbited the Moon for more than 17 years, capturing topography, surface composition, temperature readings, and radiation data. These operations allow researchers to identify alterations to the lunar terrain by comparing high-resolution before-and-after photographs captured by the spacecraft. Mr Wagner recalled that he immediately recognized the anomaly when he noticed an unusually large bright spot encircled by a dark halo, prompting him to halt his current tasks and investigate further. He noted that it was the most obvious impact debris pattern he had ever encountered in such imagery.

Named after pioneer lunar scientist Tom McGetchin, the crater is believed by researchers to have formed between April 11 and May 22, 2024. Scientists attribute the event to a comet or asteroid strike roughly the size of a three- to six-storey building. The findings regarding the McGetchin crater add to a growing body of data collected by the LRO since its 2009 launch, which suggests that the top two centimetres of the Moon's surface soil are overturned by ejected material every 80,000 years—a rate faster than previously understood.

In addition to visual photography, the LRO relies on instruments designed to detect thermal variations indicating shifts on the lunar surface. By examining the region surrounding the newly found crater, researchers discovered a 6.5-kilometre patch that remained marginally cooler during the night. This thermal anomaly, or cold spot, developed because the impact disturbed the Moon's bedrock dust and regolith, leaving the soil less dense and therefore less capable of retaining surface heat. NASA noted that the extensive reach of this cold spot demonstrates how impacts can modify the lunar landscape far beyond the boundaries of the crater itself, potentially influencing how future rover wheels interact with the terrain.

While impacts involving space rocks and other debris occur reasonably frequently on the Moon, most of the approximately 140 new craters identified annually are caused by microscopic projectiles that create features too small for the LRO to photograph. However, the spacecraft can capture craters measuring about nine metres in width created by objects just over a metre across. By utilizing LRO camera data, scientists have previously mapped seismic faults, landslides, landers, and potential lava tubes.

Mr Wagner explained that the discovery was facilitated by software that flags surface shifts by displaying them in different shades across wide-scale comparison photos. Because this automated process frequently generates false alarms, he verified the finding by searching for small fuzzy halos around pixel-wide bright points, indicating splashes of regolith around a fresh impact. Comparing these wide-scale views with close-up images confirmed the dimensions and surrounding terrain of the site.

According to Mark Robinson, chief scientist for the LRO's cameras at Intuitive Machines and lead author of one of two studies detailing the findings, the impact churned the lunar surface for more than 100 kilometres, hurling dust and rocky soil at a higher angle than anticipated. Mr Robinson's research team characterized the event in their study as a statistically rare, effectively once-in-a-lifetime observation.