Scientists have confirmed the discovery of a crater on the moon larger than the Roman Colosseum, created by a powerful impact two years ago that initially went undetected. The finding represents the solar system's biggest known impact crater carved out in recent times.

NASA's Lunar Reconnaissance Orbiter spotted the steep-sided hole on the moon's near side in May 2024, soon after it was formed by an incoming fragment of an asteroid or comet. The crater measures approximately 728 feet across—the length of two football fields—and reaches depths up to 141 feet, equivalent to three vertically stacked yellow school buses.

The moon strike escaped real-time detection by telescopes on Earth and in space. LRO's wide-angle images were not identified in the crush of data until August 2025. The spacecraft gathered more detailed pictures last fall, followed by confirmation of the discovery early this year.

Mark Robinson, chief scientist for the LRO's cameras who works at Intuitive Machines and lead author for one of the studies, reported that this latest impact churned the lunar surface for more than 66 miles. Dust and rocky soil were hurled away at a higher angle than expected.

Such a large-scale event is estimated to occur only once every 132 years, researchers said, making this discovery valuable as NASA prepares to build a base for astronauts on the moon. "This event constitutes a statistically rare, effectively once-in-a-lifetime observation," the scientists wrote in one of two studies appearing on the subject Wednesday in the journal Science Advances.

The crater—named for the late Thomas McGetchin, a former director of Houston's Lunar and Planetary Institute—is three times bigger than the previous record-holder found by the LRO a decade ago. Pockmarked since ancient times, the moon bears some of the solar system's largest impact craters, including one that stretches more than 1,500 miles across.

A separate study identified a four-mile-wide cold spot around the new crater, consistent with a loosening of the moon's top soil. Co-author David Paige of the University of California, Los Angeles, likens it to gardening. "We're now thinking of impacts as a way to garden the regolith—churning the sediments and putting stuff above that's usually below the surface," Paige said in a statement.

The LRO's numerous crater discoveries since its launch in 2009 show that the moon's top inch of soil is being overturned by ejected material every 80,000 years, faster than previously thought, according to Robinson. Contrary to the popular belief that the Apollo moonwalkers' dusty lunar footprints will last forever, they will "definitely be long gone in that time frame," Robinson said in an email.

The next step is to calculate the risk of ejected crater material striking NASA's planned moon base, Robinson added. "That information will help engineers harden structures so one won't have to worry about damage, or maybe worry less."

Bill Handel