Probability of asteroid 2024 YR4 hitting the Moon: 4.3%

Impact consequences

The diameter of 2024 YR4 is estimated to be around 60 meters. This makes it comparable to the meteoroid that struck Arizona about 50,000 years ago. That impact created a crater 1.2 kilometers in diameter and had the explosive power of 340 times the atomic bomb dropped on Hiroshima.

Earth has an atmosphere, but the Moon does not. There is no atmosphere for the asteroid to partially burn up in or break apart during its descent. The crater on the Moon will therefore be larger, estimated at about 2 km in diameter. The Moon will not be destroyed by this, nor will it be knocked out of its orbit. Such an impact would provide a spectacular show and is a prime opportunity for scientists to study the effects of a meteorite impact: after all, we have front-row seats (cameras and telescopes aimed, popcorn in hand). We might even be able to see a flash with the naked eye!

Impact drawbacks

However, such an explosive impact will kick up a significant amount of material. Most of it will fall back down, but a small portion could enter lunar orbit, creating projectiles that make future lunar missions more difficult or dangerous. A small amount could also be flung toward Earth. Fortunately, our atmosphere ensures that most of that material will burn up before it can reach the ground.

It does, however, pose a danger to the region between the Earth and the Moon, where quite a few satellites are located. Every satellite that is hit creates additional debris, which in turn poses a danger to other satellites. This could result in a cascading effect.

In short: while it is scientifically interesting, let’s hope the Moon is not hit after all. In December 2028, 2024 YR4 will come back into view, and the calculations will be refined again, so we will undoubtedly know more then!