The moon has gained a massive new battle scar after a comet or asteroid struck its eastern edge. Researchers say the collision created the largest newly formed crater found anywhere in the solar system since humans began monitoring such features.

The impact occurred two years ago, sometime between April 11 and May 22, 2024, although researchers did not notice it at the time. The space rock is estimated to have been the size of a building measuring three to six stories tall.

The collision carved out a crater measuring 728 feet, or 222 meters, across. That span is slightly longer than two football fields, while the crater’s depth of 141 feet, or 43 meters, could accommodate three school buses stacked on top of one another.

Researchers reported the discovery in a study published Wednesday in the journal Science Advances. Their crater production models suggest an impact of this magnitude should occur only once every 132 years on the moon.

“As such, this event constitutes a statistically rare, effectively once-in-a-lifetime observation,” the study authors wrote. They named the feature McGetchin crater to honor Dr. Thomas McGetchin, the late Apollo era lunar scientist who helped advance understanding of impact cratering on the moon.

Before McGetchin crater was identified, the largest contemporary impact crater found on the moon was estimated to measure 230 feet, or 70 meters, in diameter. Unlike Earth, the moon has no protective atmosphere shielding its surface from space rocks.

NASA’s Lunar Reconnaissance Orbiter helped scientists locate the bright new feature amid the moon’s heavily cratered terrain. The spacecraft has circled the moon for more than 17 years, giving researchers imagery that can reveal changes across the lunar surface.

Launched in 2009, the orbiter uses seven instruments to map the moon’s temperature, surface composition, topography and radiation. It travels from pole to pole and uses two cameras to collect images from about 60 miles, or 97 kilometers, above the surface.

The mission has allowed scientists to track at least 1,000 new impact craters and 100,000 other surface changes. Those observations include landslides and landers that crashed into the lunar surface.

About 140 new craters appear on the moon every year, with some reaching about 30 feet, or 9 meters, across. Many are produced by tiny space rocks measuring about 43 inches, or 109 centimeters, wide.

Robert Wagner, an image processing specialist at Intuitive Machines, spotted McGetchin crater on October 24, 2025. Wagner was examining stacked before and after images designed to highlight unusually bright or dark surface changes when the feature caught his attention.

“I just stopped, dropped everything, and started looking into what that spot was,” Wagner said in a statement. The detection process can be difficult because the software also flags changes caused by lighting and shadows, requiring the team to determine whether each result is genuine.

Researchers confirmed the discovery using detailed images from the orbiter’s Narrow Angle Camera. Those images allowed the team to measure the crater’s shape and dimensions while examining how the collision altered the surrounding terrain.

A separate scientific team studied information from the orbiter’s Diviner thermal instrument. The data revealed an area 4 miles, or 6.4 kilometers, wide around the crater that is 16 degrees Fahrenheit cooler at night than the rest of the region.

“Previous Diviner observations have shown that fresh lunar impact craters are often associated with ‘cold spots,’” wrote Tyler Powell, a planetary scientist and postdoctoral fellow at the Johns Hopkins University’s Applied Physics Laboratory. Scientists believe these areas develop when an impact disturbs the surface and creates a fluffier layer that retains less heat overnight.

The discovery highlights why researchers monitor the frequency and scale of lunar impacts. Such information could influence planning for a future moon base and other infrastructure as NASA’s Artemis program works toward returning humans to the surface for long term exploration.

Jeff Andrews-Hanna, a professor in the Lunar and Planetary Laboratory at the University of Arizona who was not involved in either study, compared the object with the Chelyabinsk meteor. That asteroid entered Earth’s atmosphere over Chelyabinsk, Russia, in 2013.

The Chelyabinsk asteroid measured about 55 to 65 feet, or 17 to 20 meters, and exploded in the air. Its debris damaged more than 7,000 buildings and injured more than 1,000 people, illustrating the potential consequences posed by space rocks of a similar size.