The Moon got whacked. The Moon gets whacked a lot, honestly. You can just look at its beaten, cratered surface to see that. But these days we’re pretty good at counting its scars. Since 2010, the Lunar Reconnaissance Orbiter has been circling the Moon and constantly imaging its surface, and both computers and humans check those images closely to see if there have been any new kablammos since the last photograph. There often are. The LRO can spot craters as small as 30 feet across, caused by space rocks roughly the size of a monster truck tire. (NASA’s comparison, not mine! And honestly a helpful one.) Those happen about 140 times a year. While you wouldn’t want to be under one when it impacted, those smaller collisions are basically lunar weather.
But every once in a while, something big comes in. Something big enough to get its own name. Say hello to McGetchin, the Moon’s newest crater. It’s large, and it’s fresh—having been born at some point between April 11 and May 22, 2024, the two nearest passes of the LRO. A small bright spot that hadn’t been there in the previous photo, according to McGetchin’s discoverer, Robert Wagner. “It was by far the most obvious impact debris pattern I’ve ever seen in one of these images,” Wagner said. The bright patch was typical of previously buried regolith, lunar rock and dust scattered by the impact.
Wagner discovered the new crater in images taken by the LRO’s wide-angle camera, which captures more of the surface at a time. After that it was time to point the spacecraft’s narrow-angle camera at McGetchin to make out more detail, and McGetchin looks pretty rad in close-up. The before and after of the same spot on the Moon’s surface:
Whammo! McGetchin crater, named for the late NASA lunar scientist Tom McGetchin, is a big boy. It’s 728 feet wide, almost exactly as long as the Edmund Fitzgerald and 141 feet deep. You could play a few simultaneous games of football in there, on separate, regulation fields. What sort of rock makes a crater that large? According to the paper published this week in Science Advances, it was likely a comet or asteroid about the size of a New York brownstone.
The crater is more than three times larger in diameter than the previously largest-known contemporary lunar impact crater, the paper’s authors write. “Crater production models indicate that an impact of this magnitude is expected to occur only once every 132 years on the Moon. As such, this event constitutes a statistically rare, effectively once-in-a-lifetime observation.”
On behalf of the Earth I’d like to thank the Moon for taking one for the team. A rock that size was likely behind what happened over Chelyabinsk, Russia, in 2013, when a meteor exploded in the atmosphere with a shockwave that caused more than a thousand injuries and damaged thousands of buildings. Honestly, it’s about time the Moon started earning its keep. Despite its frontline position, the Moon is not actually that useful for shielding us from potentially dangerous impactors—it is too small, and its gravity is too weak. Jupiter takes way more hits from outer Solar System bodies that might otherwise be headed our way—although it may also be constantly flinging otherwise stable asteroids and comets on potential collision courses with us. Jupiter giveth, and Jupiter taketh away. The Moon just kind of sits there and occasionally takes strays.