2024 YR4

Yesterday I heard a story on NPR about a space rock named 2024 YR4 that had at the time of the story 2.1% chance (1 in 47) of hitting earth on December 22 2032. That would be unfortunate, but let’s use this as a learning experience and explore!

Name

Before anything where the heck did the name come from?
Well, it is actually a provisional designation that was given after its initial detection and later once more observations are made could change. The name is given by the Minor Planet Center following these nomenclature rules:

Size

At this point the size of 2024 YR4 is estimated between 40 - 90 meters. As more observations are made the size and probablity of impact will be refined, but the window for observing the astroid is closing fast as it is heading back out away from Earth and soon only the biggest telescopes will be able to see it. Then we will have to wait until it returns again in 2028 on its 4 year orbit. To give an idea of its size compared to other meteors (asteroids that changed to meteors by smacking into Earth): the 2013 Chelyabinsk meteor was estimated to be 20 meters, the 1908 Tunguska meteor was estimated at 40 meters, and the Chicxulub meteor(aka dino killing one) at 10 kilometers.

Landing zone if it does hit Earth

On January 29th 2025 the International Asteroid Warning Network (IWAN) issued a potential asteroid impact notification that estimated the landing strip:

Impact Risk Corridor: The impact risk corridor for 2024 YR4, which is the region of Earth along which a potential impact could occur, extends across the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and South Asia

So even as I write this on 21/02/2025 I see that the chance of impacting Earth as already gone down to 1-in-280 (0.36%)! Good news! But wait what about our poor moon? We’ll just have to wait and see how this story develops!

Thanks for reading and feel free to give feedback or comments via email (andrew@jupiterstation.net).