Join CNN’s Wonder Theory newsletter for the latest in science news. Explore the cosmos with updates on exciting discoveries and scientific progress. A recently identified asteroid, referred to as 2024 YR4, has been deemed the most concerning asteroid ever detected. NASA reported on Tuesday that this space rock had a 3.1% chance of colliding with Earth in 2032, while the European Space Agency’s assessment indicated a 2.8% risk. The slight variance in probabilities results from each agency using different methodologies to calculate the asteroid’s trajectory and potential impact. Despite these distinctions, both figures exceed the 2.7% collision probability associated with an asteroid known as Apophis, discovered in 2004, making 2024 YR4 the most significant celestial object spotted in the last two decades.
In a subsequent update released by NASA on Wednesday, it was revealed that 2024 YR4 now carries a 1.5% chance of impacting Earth in December 2032, following recent observations post full moon. Astronomers anticipate such fluctuations as they gather more observational data. Measuring 1,148 feet (350 meters) in diameter, Apophis was previously considered one of the most perilous asteroids, scoring a 4 out of 10 on the Torino Impact Hazard Scale, a tool for classifying potential space object collisions with Earth. This rating necessitated close monitoring by astronomers. However, scientists revised this assessment after conducting a thorough analysis of Apophis’ orbit in 2021.
Forecasts suggest similar trends with 2024 YR4, which currently holds a 3 on the Torino Scale and spans an estimated 131 to 295 feet (40 to 90 meters) wide, comparable to a large building. According to the ESA, “For asteroids larger than 30 meters (98.4 feet) in size, 2024 YR4 now holds the record for the highest impact probability and the longest duration with a probability exceeding 1%.” Continual improvements in monitoring the asteroid’s orbit are expected to refine impact probabilities further.
Astronomers are utilizing various telescopes to study the asteroid’s characteristics, aiming to unveil reduced collision risks for 2032 than those indicated by current data.
Excluding Risk
Richard Binzel, the creator of the Torino Scale, noted that Apophis previously attained a Level 4, the highest rating on the scale, as it posed a greater threat of regional damage. In contrast, 2024 YR4’s Level 3 indicates a potential for local damage. Binzel introduced this scale concept at a UN conference in 1995, which was later adopted by the International Astronomical Union and published in 1999 following a meeting in Torino, Italy. Binzel underscored the importance of assessing near-Earth object risks, given their increasing detectability.
Thanks to new asteroid surveys, uncertainties in preliminary orbits may yield nonzero collision probabilities over the next century, as outlined by Binzel in his 1999 paper. To address this, an index system is proposed to convey the hazard posed by close approaches in a simple and effective manner for communication between astronomers and the public.
According to the Torino Scale, the current ranking of 3 for 2024 YR4 indicates a 1% or greater chance of collision capable of localized destruction. However, it is anticipated that with new telescopic observations, the ranking will likely be re-assigned to Level 0. Public attention and awareness by officials are warranted if the encounter is expected within a decade.
Binzel highlighted that the likelihood of impact chances fluctuating before dropping to zero is natural. The uncertainty lies in understanding the asteroid’s orbit and its proximity to Earth in the future. Astronomers are in the early stages of tracking 2024 YR4’s four-year orbit around the sun, making it challenging to predict its exact location in the coming years.
While the asteroid is expected to pass by Earth harmlessly, similar to Apophis in 2029, astronomers emphasize the importance of actively monitoring and gathering data on the space rock. Using a pasta analogy, Binzel likened the uncertainty surrounding the asteroid’s future location to a long fettuccine noodle spanning across the orbit of the moon around Earth.
Despite the uncertainty, Binzel expressed confidence in narrowing down the asteroid’s position with more data, reducing the probability of impact significantly. The asteroid’s trajectory places it near Jupiter’s orbit at its farthest point and poses a challenge due to its small size and direction away from Earth.
After its visibility in April, 2024 YR4 is not expected to be observable until June 2028 when it will safely pass by our planet again. Telescopes on the ground will track the asteroid for a few more months, with plans to utilize the James Webb Space Telescope for further observation if necessary.
While the outcome of 2024 YR4 missing Earth is anticipated, the final decision rests with nature. Binzel emphasized the ongoing tracking efforts to gather more data and ensure the safety of our planet from potential impacts.
