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In December 2024, astronomers discovered a new asteroid named 2024 YR4. Initially, they were unsure of its exact trajectory. They only had limited observations of its movement. Because the data was sparse, scientists could not predict its future path. For a short time, there was concern it might crash into Earth. That fear was quickly dismissed. However, a new worry began to emerge. It appeared the asteroid might collide with the Moon instead. Many astronomers became excited as they wanted to observe this rare event.
On March 5, 2026, NASA announced a major update. The space agency confirmed that a collision with the Moon will not occur. Scientists utilized new data from the James Webb Space Telescope to refine their calculations of the asteroid's orbit. These new measurements were far more precise. They now know the asteroid will not hit the Moon on December 22, 2032. Instead, it is expected to fly very close to the lunar surface. The asteroid will pass the Moon at a distance of 13,200 miles (about 21,200 kilometers). This new information does not mean the asteroid changed its path. It simply means our understanding has become much clearer.
Before these latest observations, earlier analysis suggested a possible impact risk. It took a long time to reach this final conclusion. The problem was that the asteroid became too faint to see. It was too dim for ground-based telescopes in the spring of 2025. Terrestrial telescopes could not gather enough data. Astronomers needed the powerful, space-based Webb telescope. The Webb telescope is much more sensitive. It can detect the faint light of the asteroid from deep space. This specialized equipment allowed experts to make the final determination. The Moon is safe.
Asteroid 2024 YR4 was first spotted by the ATLAS system. This system uses telescopes in Hawaii, Chile, and South Africa. The first sighting occurred on December 25, 2024. When it was first seen, astronomers thought it might hit Earth. At that time, it received a rating of 3 on the Torino Scale. The Torino Scale rates the danger level of asteroids. A rating of 3 is in the yellow zone. This means the object requires attention from both scientists and the public. The only other asteroid to reach this level was the famous asteroid 99942 Apophis. Just like with Apophis, there was a lot of excitement. However, by February 2025, scientists learned that 2024 YR4 would not strike Earth in 2032. Its rating dropped to near zero. The danger had passed.
In February 2025, after an Earth impact was ruled out, the odds of hitting the Moon were estimated at 1.8% (a chance of 1 in 56). Over the following months, as astronomers gathered more data, the calculated impact probability fluctuated. This is a normal part of the process as initial observations often create a wide range of possible paths, some of which include an impact. With each new observation, the predicted path is refined. This process continued until the definitive observations from the James Webb Space Telescope in early 2026 confirmed the asteroid will miss the Moon entirely. The danger has completely passed.
Observations from the Webb telescope also helped astronomers determine the size. NASA reported that 2024 YR4 is between 174 and 220 feet in diameter. That is about the size of a 15-story building. Earlier estimates placed it at around 150 feet. So, it is slightly bigger than first thought. An object of that size hitting Earth could destroy a city. While it will not hit Earth or the Moon, it is a very large space rock.
On April 8, 2025, scientists from NOIRLab reported observations. They used the Gemini South telescope to study the asteroid. These observations revealed the asteroid's unusual shape and likely origin. Scientists said it has a hockey-puck-like shape. They also said it most likely came from the main asteroid belt. Both findings were unexpected for scientists. Bryce Bolin said: "This find was rather unexpected since most asteroids are thought to be shaped like potatoes rather than flat disks." Regarding the origin, Bolin said: "We are a bit surprised about its origin in the central main asteroid belt."
The International Astronomical Union has used the Torino Scale since 1999. It helps categorize asteroids that could hit Earth. An object with a score of 3 is in the yellow zone. The description states that a close encounter merits attention by astronomers. Current calculations indicate a 1% or greater chance of collision. The description adds that new observations will likely lead to Level 0, meaning no hazard. Most new asteroids are initially listed with a low likelihood. Their probability often rises at first. Then it drops to zero. This happens because scientists start with a wide, uncertain path. More observations shrink that path. An impact looks more likely until the path narrows enough to show it will miss. This is exactly what happened with asteroid 2024 YR4.
If we find an asteroid on a collision course, we will be prepared. Scientists have tested a method to move an asteroid. The mission was called the Double Asteroid Redirection Test, known as DART. In 2022, the DART spacecraft crashed into a small asteroid moon named Dimorphos. The goal was to see if we could change its orbit. The test was a great success. Dimorphos was much larger than asteroid 2024 YR4, measuring 525 feet across. This test gives scientists confidence. They know they could protect Earth from a future threat. While 2024 YR4 will not hit anything, the knowledge gained shows we are learning how to watch our solar system. We are keeping our planet safe.