Asteroid 2024 YR4 impact risk updated to 1.8%

The probability of asteroid 2024 YR4 impacting Earth has risen from 1.2% on January 29 to 1.8% on February 6, 2025, according to ESA’s Planetary Defense Office. The potential impact date remains December 22, 2032.

Astronomers used simulations to analyze the asteroid’s potential trajectory, examining over 500 possibilities.

The red line in the simulation graphic represents the range of possible paths the asteroid could take. This line is approximately 160 times wider than Earth’s diameter, measuring about 2 million km (1.24 million miles) in length. For comparison, Earth is about 12 756 km (7 926 miles) wide.

The simulation shows a higher concentration of red dots closer to Earth, suggesting that the distribution is not uniform along the entire length of the line. The impact probability is estimated using the ratio of the Earth’s width to the width of the line, calculated as 1/54, or approximately 1.8 %.

The probability of impact may change as more observational data becomes available. Astronomers anticipate fluctuations, with the probability initially increasing before declining.

The uncertainty in the asteroid’s characteristics contributes to fluctuations in impact probability. Its exact size remains unknown, but current estimates suggest a diameter between 40 and 90 m (131 and 295 feet).

The asteroid is currently moving away from Earth in a receding orbital path, making it more challenging to observe. Larger telescopes are required to track 2024 YR4, and additional observational data will help refine its trajectory to determine whether an impact is possible.

By April 2024 YR4 will be too faint for observation using medium-sized telescopes (4 m-class) and tracking will require advanced optics, such as the James Webb Space Telescope or the European Southern Observatory’s Very Large Telescope (VLT), which has 8 m-class optics.

The asteroid will become unobservable in May and remain out of sight until June 2028, potentially limiting astronomers’ ability to accurately predict its trajectory and rule out a possible impact in 2032.

Asteroid 2024 YR4 was detected at the Asteroid Terrestrial-impact Last Alert System (ATLAS) in Chile on December 27, 2024. Initial observations provided only limited data on its orbit, but follow-up studies using telescopes worldwide allowed astronomers to better define its trajectory and calculate an impact probability of 1.2%, placing the asteroid at level 3 on the Torino Scale.

The Torino Scale is used to assess the impact hazard of near-Earth objects (NEOs), categorizing potential impacts from 0 to 10, where 0 indicates no risk and 10 represents a certain, catastrophic collision. The scale considers both the probability of impact and its potential consequences.

A level 3 classification on the Torino Scale indicates an event meriting attention by astronomers due to a close encounter with a 1% or greater chance of impact. While such an event does not pose an immediate public concern, it warrants further observations and refined calculations to better determine the asteroid’s trajectory and potential risks.

The only asteroid ever to receive a higher rating on the Torino Scale than 2024 YR4 is Apophis, which gained widespread attention in 2004.

Initial calculations suggested a concerning possibility of impact with Earth in 2029, leading to an initial rating of 4 on the scale. As additional data became available, astronomers refined Apophis’s trajectory, significantly reducing the estimated probability of impact.

By 2006, the risk level was downgraded, and further refinements over the years confirmed that Apophis posed no threat to Earth for at least the next century. In 2021, new radar observations ruled out any possibility of impact in 2068, further securing its status as a non-hazardous object.

References:

¹ 2024 YR4 flyby geometry, or 1.8% of What? – ESA – February 6, 2025

² Asteroid 2024 YR4 triggers planetary defense procedures – The Watchers – February 3, 2025