In February, I wrote about an asteroid (2024 YR4) that originally had a 3.1% projected chance of hitting the Earth in 2032. As its orbit became more predictable, this was lowered to virtually 0%. Recently they upgraded the chance of asteroid 2024 YR4 hitting the Moon to 3.8%.
A team of astronomers recently studied the asteroid in more detail and found that 2024 YR4 likely came from the asteroid belt between Mars and Jupiter and has an unusually flat, disk-like shape, similar to a hockey puck. Most asteroids are believed to be shaped like potatoes rather than flat disks.
Astronomers discovered the asteroid 2024 YR4 in December 2024 (hence the “2024” in its name). A team studying the asteroid recently determined that the asteroid is rotating very quickly, about once every 20 minutes, and estimated its size is between 98 to 213 feet (30 to 65 meters) wide.
2024 YR4 is one of the largest objects in recent history with the potential to strike the Moon. If it did hit, scientists would have the opportunity to study how the size of an asteroid relates to the size of the crater it creates on an object with little gravity.
Of course, an asteroid striking the Moon is not a novel event. One need only look at the Moon to see that it has been bombarded with asteroids in its past. Because the Moon lacks an atmosphere, Teutonic plates, and volcanic activity, the craters that we see are all due to impact collisions. Most of these impacts probably came during the time period known as the Great Bombardment. During this period, about 3.9 billion years ago, our entire solar system experienced a period of intense bombardment by asteroids and comets. These impacts formed massive impact basins and craters, which are clearly visible on the Moon’s surface.
Asteroid impacts have also thrown out rocks from the Moon, some of which have landed on Earth as lunar meteorites. Smaller impacts from meteoroids are still occurring on the Moon today.
If a large asteroid such as 2024 Y4 were to crash into the Moon, it would create a large crater that would eject material from the surface, but that would be the extent of the damage. There aren’t any asteroids large enough to split the Moon apart or knock it off its orbit around the Earth. In fact, the total mass of all the known solar system’s asteroids combined is less than the mass of the Moon.
Because of our human settlements, asteroids that would cause widespread damage on Earth would not cause the same problems on the Moon, even though there’s no lunar atmosphere to slow them down. There’s simply nothing to destroy on the Moon. Damage on Earth is not about the rock underneath us being disturbed, but about the cities, climate, and lives that would be impacted.
Remembering the chance of impact is less than 4%, it is unlikely that this asteroid will glance the Moon in 2032, but scientists would be excited if it did.
Angela Rieck, a Caroline County native, received her PhD in Mathematical Psychology from the University of Maryland and worked as a scientist at Bell Labs, and other high-tech companies in New Jersey before retiring as a corporate executive. Angela and her dogs divide their time between St Michaels and Key West Florida. Her daughter lives and works in New York City.
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