Asteroid 2024 YR4 has gained attention due to its considerable size, estimated between 40 and 100 meters (130 – 330 feet), and a potential impact risk in 2032. This has placed it at the top of the European Space Agency’s (ESA) risk list, making it a priority for further observation and trajectory refinement.
Its impact probability has been calculated at 1.3% by NASA’s Jet Propulsion Laboratory (JPL) Center for Near-Earth Object (NEO) Studies and ESA’s Near-Earth Objects Coordination Centre (NEOCC) using the NEO Dynamic Site (NEODyS).
This classification places the asteroid at level 3 on the Torino Scale — a method used to assess the impact hazard of near-Earth objects (NEOs). The scale categorizes potential impacts on a scale from 0 to 10, with 0 indicating no risk and 10 representing a certain and catastrophic collision. It takes into account both the probability of impact and the 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.
“We have been quite active since early January in order to obtain as many observations as possible to constrain the trajectory of the object to the best possible,” scientists at ESA’s NEO Coordination Center said.
“For that purpose we have gathered observations from ESA’s OGS telescope in Tenerife and, thanks to our long-standing collaboration with ESO, we also obtained observations done with the VLT telescopes. We have obtained exquisite astrometry and color data in order to both improve the trajectory knowledge and the determination of the physical properties of the object.”
Thanks to these efforts, and to the efforts of the international asteroid community, the impact threat from this object has been neatly determined.
Scientists anticipate that future observations will reduce uncertainties in 2024 YR4’s trajectory and impact probability. Based on current data, the Near-Earth Asteroid (NEA) is likely to be removed from the risk list within a few weeks.
Asteroid 2024 YR will remain observable until early April 2025. If it is not removed from the risk list by then, it will become visible again in 2028, providing another opportunity for refined calculations.
The projected impact risk corridor spans the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and South Asia.
The asteroid will be relatively faint and will likely require large telescopes (2 m or larger) for observation by the end of the 2025 observability window.
The detection of the asteroid has activated two United Nations-endorsed global asteroid response groups. The International Asteroid Warning Network (IAWN), which includes space agencies, observatories, and research institutions, has begun making additional observations to refine the asteroid’s trajectory. Their goal is to reduce uncertainties in its orbit and improve the accuracy of impact risk assessments.
The Space Mission Planning Advisory Group (SMPAG) has been alerted. This organization is made up of national space agencies and international specialists, and is responsible for assessing possible response strategies.
If needed, SMPAG could propose mitigation efforts, such as a deflection mission. One option would be to send an intercepting spacecraft to alter the asteroid’s course, a method successfully tested during NASA’s Double Asteroid Redirection Test mission in 2022.
These efforts are part of a coordinated planetary defense strategy aimed at tracking and, if necessary, responding to asteroid threats using established scientific methods.
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. This classification indicated a close encounter with a small but significant chance of collision, warranting careful monitoring and further observations.
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.
Apophis, approximately 370 m (1 210 feet) in diameter, remains one of the most studied asteroids due to its close approaches.
Apophis will pass within 31 600 km (19 600 miles) of Earth on April 13, 2029, but with no risk of impact.
References:
1 INTERNATIONAL ASTEROID WARNING NETWORK (IAWN) POTENTIAL ASTEROID IMPACT NOTIFICATION – IAWN – January 29, 2025
2 ESA’s Planetary Defence Office is keeping a very close eye on 2024 YR4 – ESA – January 31, 2025