2024 YR4 is one of about 20,000 Apollo-type asteroids that orbit the sun from about the same ... [+] distance as Earth, so are a potential threat.gettyThe chances of asteroid 2024 YR4 striking Earth this week increased to 1-in-32 after NASAs Center for Near-Earth Object Studies updated the impact probability then dramatically fell to just 1-in-67 after some more observations.On February 18, 2025, NASAs Center for Near-Earth Object Studiesupdated the asteroid's impact probability to 3.1%, the highest ever recorded for an object of this size. However, according to NASA, subsequent data collected overnight reduced this probability to 1.5% as of February 19, 2025.Risk CorridorWhat is 2024 YR4? Discovered on December 27, 2024, by the Asteroid Terrestrial-impact Last Alert System in Chile, asteroid 2024 YR4 measures approximately 130 to 300 feet (40 to 90 meters) in diameter. According to IAWN, its potential impact date is projected for December 22, 2032, with the "risk corridor" covering the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and South Asia.Astronomers worldwide and even the James Webb Space Telescope are now busy making additional observations to try to refine the exact trajectory of 2024 YR4. The recent full moon in the same region of the sky (Canis Major) had led to a paucity of observations, which resulted in a gap in observations. However, observations resumed this week and are already yielding results.Large ground-based telescopes currently being used to study 2024 YR4 include the Gemini telescopes in Hawaii and Chile,Speck In SpaceUncertainty about 2024 YR4 is purely down to its recent discovery. 2024 YR4 orbits the sun every four years, crossing Earth's orbit once per orbit. Since it was only discovered in December, it's only been tracked for a few months, a tiny fraction of its entire orbit. "The tiny bit of tracking creates a large uncertainty for where the asteroid will be on any date far into the future," said Richard Binzel, Professor of Planetary Science at the Massachusetts Institute of Technology, in an email. "In 2032, that uncertainty happens to include Earth's tiny speck in space."Close EncounterBinzel is the inventor of the Torino Impact Hazard Scale, a tool for categorizing potential Earth impact events. Despite the lowering of its chance of an impact, 2024 YR3 is still classified as 3 on a scale of 10, summarized as "a close encounter, meriting attention by astronomers.""While the probability changes, the hazard rating doesn't," said Binzel. "2024 YR3 remains Torino Scale 3." However, Binzel points out that this category states that "most likely, new telescopic observations will lead to re-assignment to Level 0."It's something of a race against time since after April, the asteroid wont be visible to telescopes again until late 2028 when 2024 YR4 next comes within Earth's vicinity.Uncertainty Region"Eventually, we expect the probability to fall to zero and reach Torino Scale 0 (all clear!)," said Binzel. "The uncertainty region, which looks like a long spaghetti of fettuccine string, shrinks as we get tracking data over a longer and longer piece of the asteroid's orbit." Eventually, this spaghetti string will shrink to a single grain because astronomers will have tracked the asteroid's complete orbit.One analogy is hurricane tracking, where, at first, the path of a hurricane has great uncertainty but becomes very well-defined the longer the storm is tracked. "Hurricanes tracking can be refined in a matter of days or a week," said BInzel. "For asteroids, it can take months or even years."What Happens NextMany asteroids initially considered a potential threat have been reclassified as harmless after further analysis and that's exactly what seems to already be happening. "I expect we will continue to see that probability number bounce around, even increase before finally, we resolve it as being 0," said Binzel, stressing that it's merely the scientific measurement method and orbit calculation methods being done in public. "It might seem confusing or worrying, but it is simply the nature of this particular science," he said. "Astronomers do not wish to keep any secrets, as anyone can just look up. The sky is free to everyone."Although the absence of the moon from the evening night sky makes it easier to observe 2024 YR4, our natural satellite is not completely out of the woods. According to NASA, current calculations estimate an 0.8% impact probability a 1-in-125 chance that the asteroid will hit not Earth, but the moon.Wishing you clear skies and wide eyes.