Scientists have identified a newly formed crater on the moon that is larger than Rome’s Colosseum, created by a powerful impact that went unnoticed when it occurred two years ago.
The steep-walled lunar crater measures roughly 728 feet wide and reaches depths of up to 141 feet. Researchers say it is the largest known impact crater formed anywhere in the solar system in recent times.
Events of this scale are expected only about once every 132 years, according to the researchers. The discovery offers an unusual opportunity to study fresh lunar impacts as NASA moves ahead with plans to establish a base for astronauts on the moon.
“This event constitutes a statistically rare, effectively once-in-a-lifetime observation,” scientists wrote in one of two studies on the discovery published Wednesday in the journal Science Advances.
NASA’s Lunar Reconnaissance Orbiter, or LRO, detected the crater on the moon’s near side in May 2024, shortly after it was excavated by a fragment from an asteroid or comet.
Despite the force of the lunar strike, telescopes on Earth and in space did not detect the impact in real time.
The LRO’s wide-angle images were initially lost amid the vast volume of spacecraft data and were not recognized until August 2025.
More detailed images were collected by the spacecraft last fall, with the discovery confirmed early this year.
The crater was named for the late Thomas McGetchin, a former director of Houston’s Lunar and Planetary Institute. It is three times larger than the previous record-holder, which the LRO found a decade ago.
Scarred by impacts since ancient times, the moon is home to some of the solar system’s biggest craters, including one spanning more than 1,500 miles.
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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, according to Mark Robinson, chief scientist for the LRO’s cameras who works at Intuitive Machines.
Robinson was the lead author for one of the studies.
A separate study identified a 4-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, he added.
“That information will help engineers harden structures so one won’t have to worry about damage, or maybe worry less.”