Recent international efforts have significantly refined the impact risk estimates for asteroid 2024 YR4, reducing the probability of an Earth collision in 2032 from 3% to less than 0.001%, while highlighting a residual risk to the Moon.
Key Points at a Glance
- Initial observations in December 2024 indicated a 1.3% chance of Earth impact by asteroid 2024 YR4 in 2032.
- Subsequent data collection increased this probability to 3%, prompting intensified global monitoring.
- Recent observations have reduced the Earth impact risk to below 0.001%, though a minor risk to the Moon remains.
- The asteroid’s size is estimated between 40 and 90 meters, comparable to the object that caused the Tunguska event.
In December 2024, astronomers identified a new near-Earth object, designated 2024 YR4, which quickly became a focal point for the global scientific community due to its potential collision course with Earth. Initial calculations suggested a 1.3% probability of impact on December 22, 2032, with the asteroid’s dimensions estimated between 40 and 90 meters—comparable to the size of the object responsible for the 1908 Tunguska event. These early assessments assigned 2024 YR4 a Torino scale rating of 3, indicating a situation meriting close attention by astronomers.
By mid-February 2025, the estimated impact probability peaked at 3%, marking the highest risk level ever recorded for an asteroid of this size. This escalation prompted an international observational campaign, with researchers from the University of Helsinki playing a pivotal role. Postdoctoral researchers Zuri Gray and Grigori Fedorets utilized the 2.5-meter Nordic Optical Telescope (NOT) in La Palma, Canary Islands, to gather precise positional and rotational data on 2024 YR4.
Gray emphasized the importance of these observations: “We have been focusing on the asteroid’s precise position and motion, and to analyze its rotation, size, and shape. This information is crucial for better predicting the asteroid’s future trajectory, and ultimately refining its impact probability.” Fedorets added, “Our recent observations continue to demonstrate the vital role that NOT plays in planetary defense efforts on a global level.”
The collaborative efforts yielded significant results. Following a brief observational hiatus due to lunar brightness, the Helsinki team was among the first to resume data collection. Their findings contributed to a dramatic reduction in the Earth impact probability, now calculated to be below 0.001%.
However, the updated trajectory analyses introduced a new consideration: a residual impact risk to the Moon. While the likelihood remains low, it underscores the necessity for continued monitoring and analysis.
Asteroid 2024 YR4 serves as a pertinent example of the dynamic nature of near-Earth object tracking and the critical importance of sustained international collaboration in planetary defense. The rapid refinement of impact probabilities highlights the effectiveness of coordinated observational campaigns and the vital role of advanced technologies in safeguarding our planet and its celestial neighbors.
Source: University of Helsinki
