Asteroid 2024 YR4 no longer threatens Earth. Instead, updated calculations show about a 4.3 percent chance that the 60-meter-wide rock could strike the Moon on Dec. 22, 2032, at a velocity of about 14 kilometers per second. The impact would release energy equivalent to about 6.5 million tons of TNT and carve out a crater roughly one kilometer across. That would make it the most energetic lunar impact recorded during the era of modern observation.
Rather than debating how to prevent the collision, researchers have focused on what would happen next. In a recent preprint published in Astrophysics, a team modeled the physical effects of a lunar impact and laid out an observation timeline detailing the first seconds through the years that follow. Their work turns a low-probability event into a chance to watch a major lunar impact unfold in real time.
The First Minutes of Asteroid 2024 YR4
The impact would announce itself with light. The researchers estimate that the collision could produce a flash reaching a brightness between –2.5 and –3 magnitude (a flash as bright as Jupiter in the night sky) and lasting several minutes. That level of brightness would make the event detectable from Earth with small telescopes under favorable conditions.
After the flash fades, heat would dominate the signal. The impact would melt lunar rock at temperatures around 2,000 Kelvin. As that molten material cools over hours and possibly days, it would emit infrared radiation that telescopes could track. By measuring how quickly the crater cools, researchers could estimate how much material melted and how the lunar surface absorbs and releases heat.
The preprint identifies when optical and infrared instruments would have the best chance to capture these signals, aligning observation windows with the predicted timing of the flash and the thermal afterglow.
Shaking the Moon
The collision would also send energy through the Moon’s interior. Based on their calculations, the impact could generate a moonquake with a magnitude of about 5, relative in strength to a moderate earthquake on Earth. Seismometers (instruments that measure ground vibrations) on the lunar surface could detect shaking across large distances.
These vibrations would provide insight into how the Moon’s crust transmits motion and how seismic waves travel through its interior. Because researchers can estimate the energy of the impact in advance, they would know the source strength of the quake, making the event especially useful for interpreting seismic data.
Debris That Could Reach Earth
Not all of the impact material would stay on the Moon. Simulations show tens to hundreds of millions of kilograms of rock could escape the Moon’s gravity, depending on the angle of impact. Some of that debris would remain in the Earth–Moon system, and a small fraction could eventually reach Earth.
In certain scenarios, fragments could begin arriving within days, increasing meteor activity for a short period. Over months and years, some larger pieces could survive passage through Earth’s atmosphere and land as lunar meteorites. The researchers also note that some meter-scale fragments could remain near Earth for decades, where sky surveys could track them long after the initial event.
The researchers do not treat these effects as isolated events. They align each phase with specific instruments, from high-speed optical cameras trained on the Moon at the moment of impact to infrared telescopes tracking the cooling crater, lunar seismometers recording the shock, and meteor networks monitoring debris days to months later.
By combining predictions for the flash, the heat, the shaking, and the movement of debris, the preprint outlines a coordinated timeline that spans from seconds after impact to years later. If 2024 YR4 strikes the Moon, scientists would not be scrambling to respond. They would already know when to look and what signals to expect.
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Article Sources
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- This article references information from the recent preprint published in Astrophysics: Observation Timelines for the Potential Lunar Impact of Asteroid 2024 YR4
