If YR4 hits the Moon, the consequences could reach Earth

On December 22, 2032, asteroid 2024 YR4 has a 4% chance of actually hitting the Moon. If it happens, it will release enough energy to be the equivalent of hitting our closest neighbor with a medium-sized thermonuclear weapon.

There is a positive side to every situation. In 2032, the Moon itself could have a particularly bright side if it is struck by an asteroid 60 meters wide. The odds of such an event remain relatively small (only about 4%), but not negligible.

As , scientists are already starting to prepare for both the bad – massive risks to satellites and huge meteors raining down on a large part of the planet – and the good – a once-in-a-lifetime opportunity to study the geology, seismology and chemical composition of our closest neighbor.

A new study, last week on arXiv, looked at the upside of all the potentially interesting science we could do if a collision happens.

If YR4 hits the Moon, it will be a fortuitous event for physicists who study high-energy impacts. A crater approximately 1 km wide and 150 to 260 m deep should form, with a central pool of molten rock measuring approximately 100 m. Comparing it in size to other craters scattered across the Moon will help us understand its bombardment history.

The impact will also trigger a global “moonquake” of magnitude 5.0. That would be the strongest lunar earthquake ever detected by any seismometer on the Moon. Observing the propagation of the lunar earthquake caused by the impact will shed light on the Moon’s interior and help researchers understand its composition without needing to blow it up with anything artificial.

And the consequences that will reach Earth

One last piece of the scientific puzzle will be the debris field created by the explosion. It is expected that until 400 kg of this material survive re-entry to Earthessentially creating a free “large-scale” lunar sample return mission for astronomers.

At its peak, just in time for Christmas 2032, simulations predict that by 20 million meteors per hour hit our atmosphere, at least on the planet’s “leading edge” — most of them visible to the naked eye. These would include around 100 to 400 fireballs per hour.

Now the bad news: those 400 kg of meteors have to fall somewhere, and it looks like the target falls directly on South America, North Africa and the Arabian Peninsula.

Still, perhaps more dangerous is the risk to the mega-constellations of satellites that play such an important role in our modern navigation and Internet systems.

An event of this type could trigger “Kessler Syndrome” and bringing down the entire network over several yearswhile also preventing us from safely putting anything else into orbit for much longer.