NASA's Lunar Reconnaissance Orbiter has found a 728-foot-wide impact crater on the Moon's eastern limb, created between April and May 2024 by a building-sized asteroid or comet. The discovery gives scientists a rare look at how the lunar surface changes after a major collision.
A recent impact on the Moon's eastern limb has left behind the largest new crater seen in the Solar System since the start of the space age. NASA's Lunar Reconnaissance Orbiter (LRO) team identified the feature, now named McGetchin crater after lunar scientist Thomas McGetchin, during a routine scan of global lunar images. The crater stood out as a bright spot with a dark halo-signs of freshly disturbed lunar soil from a powerful collision.
Discovery and identification
NASA researcher Robert Wagner first noticed the McGetchin crater in May 2024 while comparing new LRO images with older ones. By checking images from May and April 11, 2024, the team narrowed down the impact to that window. The object that hit the Moon was likely the size of a three- to six-story building and struck the near side's eastern edge, carving out a hole 222 meters (728 feet) wide and 43 meters (141 feet) deep. McGetchin is about three times larger than the previous biggest new crater found by LRO, which shows how rare such large impacts are-scientists estimate they happen only once a century or less.
To confirm the find, researchers used both automated software and manual checks. The software can flag many false positives due to changing sunlight or minor surface shifts, but in this case, the debris pattern and thermal signature were clear. The team followed up with sharper images and thermal scans to verify the crater's size and the extent of the debris.
How the crater was studied
LRO carries both wide-angle and narrow-angle cameras, allowing for global mapping and close-up views. After spotting the new crater, the team used the narrow-angle camera to get images at about one-meter resolution, confirming the crater's dimensions and the spread of ejected material. The impact also created a thermal anomaly: LRO's Diviner instrument showed that a region about four miles wide around the crater is roughly 9 degrees Celsius (16 degrees Fahrenheit) cooler at night than nearby ground. This "cold spot," described in a recent Nature study, is caused by the impact fluffing up the lunar soil, which then loses heat more quickly at night.
The cold spot stretches well beyond the crater itself, showing that big impacts can change the lunar surface over a much larger area than just the crater rim. These changes could affect how future lunar rovers and landers perform, since the altered soil may behave differently-something NASA's Artemis missions and other lunar projects will need to consider.
How often do big lunar impacts happen?
Over 17 years, LRO has cataloged at least 1,000 new impact craters and over 100,000 other surface changes from impacts or debris. Most new craters are much smaller than McGetchin, with the smallest ones LRO can spot measuring about 9 meters (30 feet) across-usually made by objects about a meter wide. Most impacts come from even smaller particles that leave marks too faint to see from orbit. Because the Moon has no atmosphere, incoming objects-asteroids or comet fragments-hit the surface at full speed. Scientists at places like MIT and the Max Planck Society also study these impacts.
While McGetchin stands out for its size, it's part of the ongoing process that shapes the Moon's surface. Detecting and studying these events depends on how often and how closely the Moon is imaged, as well as improvements in software that can spot changes. NASA and its partners continue to refine these tools.
Why this matters for lunar science
Finding the McGetchin crater shows the value of long-term, high-resolution monitoring of the Moon. By comparing new and old images, scientists can spot not just big impacts but also subtle changes like landslides or tectonic shifts. The techniques used here are similar to those in other planetary science work, such as the study of lunar surface anomalies.
As NASA and other space agencies plan more lunar missions, knowing how often and how dramatically the surface changes is important for both safety and science. The McGetchin impact gives researchers a rare chance to study the immediate and longer-term effects of a major collision, which will help guide future robotic and crewed missions. LRO's data shows that the Moon's surface is still changing, shaped by ongoing impacts that can be tracked and measured with today's instruments.
To understand these changes, scientists use a mix of optical and thermal images from orbit. Change-detection software compares images from different times to highlight new features or disturbances. Thermal instruments like Diviner reveal how the surface holds or loses heat, showing changes that regular cameras can't see. Together, these methods help researchers piece together when and how impacts happen, building a detailed record of how the Moon's surface evolves over time.
