What began as a simple sighting has now become a global alert. This asteroid , 2024 YR4, was detected at the end of last year and initially held little significance. But as the days passed, it managed to capture the attention of the scientific community and public opinion due to its potential risk of impact with Earth in 2032.
Discovered on December 27, 2024 by one of the telescopes in the ATLAS ( Asteroid Terrestrial-impact Last Alert System ) network of the University of Hawaii located in Río Hurtado (Chile), this celestial object, with an estimated diameter of between 40 and 90 meters, has been classified as dangerous at level 3 on the Turin scale , which indicates that it deserves constant monitoring by astronomers.
And the concern was such that the United Nations issued an alert calling for more telescopes to join in monitoring this body wandering in space. Amid this unprecedented event, it was learned that the international organization also decided that 2029 would be the International Year of Asteroid Awareness and Planetary Defense .
“We are simply reporting that, as experts and according to our protocols, we have to pay special attention to this particular asteroid ,” explained the Spaniard Juan Luis Cano, coordinator of NASA ‘s Planetary Defense Office , who sent a message of reassurance regarding the activation of the protocol.
However, the message of reassurance clashes with a worrying reality. Generally, when a space rock is discovered and the degree of probability of collision with Earth is determined, subsequent studies and observations lower that percentage of danger. This wasn’t the case here.
n one week of observations, we have gone from a 1 in 83 chance of the asteroid crossing paths with planet Earth to a 1 in 43 chance.
Since its detection, scientists have analyzed 2024 YR4’s orbit to more precisely determine its trajectory and the likelihood of impact with Earth on December 22, 2032.
What started out as 1.3% has risen to 2.3%, according to the most recent calculations from the Center for Near-Earth Object Studies (CNEOS) at NASA ‘s Jet Propulsion Laboratory (JPL) , a figure that the European Space Agency (ESA) has confirmed with its own estimate of 2.27%. While this figure is low, it is sufficient to keep the asteroid under observation until any risk is ruled out.
International protocol establishes that any asteroid with more than a 1% probability of impact and a size greater than 50 meters must be reported to the UN Office for Outer Space Affairs (UNOOSA). Consequently, on January 29, the International Asteroid Warning Network (IAWN) officially notified its existence, triggering international surveillance.
Thus, on February 3, the UN’s Space Mission Planning Advisory Group (SMPAG ), which is responsible for coordinating the international response to possible asteroid impacts, announced that it would continue monitoring asteroid 2024 YR4 until the probability falls below 1%. But far from decreasing, that probability actually increased.
“ A close encounter with Earth that deserves the attention of astronomers and the public ,” the scientists who compiled the Torino scale note, referring to level 3 asteroids. Despite this, scientists are confident that the probability of impact will decrease in the coming months as more precise data on its orbit becomes available.
According to Kelly Fast, a NASA planetary defense officer, the asteroid has a peculiar orbit that takes it through the inner solar system, passing close to the Sun and Earth, before moving away toward the region between the orbits of Mars and Jupiter.
The discovery of 2024 YR4
Mariano Ribas, head of Scientific Outreach at the Buenos Aires City Planetarium, explained to Infobae how this asteroid was discovered: “It has a catalog entry, an identification that is 2024 YR4 and it was discovered very late last year, on December 27, by one of the telescopes in the Atlas network, which is a system for monitoring and searching for near-Earth objects . One of its telescopes, which is in Chile, is the one that found this object, which has an estimated size of around 50 or 60 meters. There is talk of a minimum of 40, a maximum of 100.”
And he added: “From that moment on, it begins to be monitored, its trajectory tracked day by day, and an orbit is estimated. From that estimate, it was determined that on December 22, 2032, it will pass very close to Earth. That, in real terms, is about 50,000, 100,000, or 150,000 kilometers, with margins up and down. The initial probability of impact would be around 1.3%, which is significant enough to warrant special monitoring. And precisely because this percentage exceeds 1%, the UN-mandated planetary security protocol is activated.”
“ This estimate has been changing in recent days based on more precise orbital parameters. It was raised to 1.6% and then to a little over 2%. In some studies, it’s even higher. For example, there’s an article in the journal Sky & Telescope that cites a study that suggests a 3 to 6% chance. So we’re on an upward trend. In many other cases, these percentages are gradually being eliminated or erased, but not in this case, which is striking,” Ribas said.
Comparison with other asteroids
The case of 2024 YR4 is reminiscent of that of the asteroid Apophis, discovered in 2004. Initial estimates at the time indicated a 2.7% probability of impact by 2029, giving it a level 4 rating on the Torino scale . However, subsequent studies ruled out any risk, and it was confirmed that it will pass within 38,000 kilometers of Earth without posing a threat.
Unlike Apophis, which has a diameter of 185 meters, 2024 YR4 is a smaller object. While it does not pose a global threat, its impact could cause significant regional damage. According to estimates, a landfall would be equivalent to the explosion of eight megatons of TNT, an energy 500 times greater than that of the Hiroshima bomb. If it exploded over the ocean, the impact could trigger a massive tsunami that would hit several countries.
On December 17, 2028, 2024 YR4 will pass at a distance of approximately eight million kilometers from Earth. This flyby will be key to obtaining more information about its size, composition, and orbit. “Right now, its status is that of an asteroid worthy of astronomers’ attention,” NASA explained.
In which countries could asteroid 2024 YR4 fall?
Astronomer Daniel Bamberger calculated that, if an impact were to occur, the potential collision zone would extend from the eastern Pacific Ocean to southern Asia, passing through South America and Africa. However, these estimates are preliminary and could change with new data.
The alleged impact could occur in a strip of the Earth stretching from Colombia, Venezuela, and northern Brazil to mid-Africa, India, and Myanmar. This trajectory includes a large portion of the sea, but also heavily populated areas.
“If it were to hit Earth, it wouldn’t cause a global tragedy, as happened, for example, some 65 million years ago, when an asteroid about nine or ten kilometers in diameter hit what is now the Yucatán Peninsula and caused the disappearance of more than 90% of plant and animal species, including the dinosaurs,” astronomer Diego Bagú explained to Infobae .
“But an object of this type would cause, for example, tremendous damage in the area where it impacted. The closest known record of a phenomenon of this type we have occurred in 1908, a little over 100 years ago in Tunguska, in northern Siberia, Russia. It was at the moment when an asteroid measuring about 50 meters entered the atmosphere, and although it didn’t impact the Earth’s surface, the pressure and temperature it raised in the Earth’s atmosphere were such that it exploded, the shock wave leveled an entire forested area of more than 2,100 hectares, which was absolutely decimated by the shock wave from the explosion of an asteroid of this type,” added the former director of the La Plata planetarium.
Possible mitigation strategies
If the probability of impact remains high in the coming years, the international community would have sufficient time to plan a response. In 2022, NASA’s DART mission demonstrated that it is possible to deflect an asteroid’s trajectory through a kinetic impact. A similar method could be employed with 2024 YR4 if deemed necessary.
“The only time in history that a technique to deflect an asteroid was tested occurred two years ago, when the NASA and European Space Agency DART space probe impacted an asteroid about 100 meters in diameter. It was the asteroid Dimorphos, causing, yes, a change in its orbit . Basically, the impactor was a ship a little larger than a car. The objective was to hit this asteroid and cause a minimal change in its speed. But that minimal change in speed, over the days and weeks, generated a change in its orbit, a change in its path,” Bagú explained.
And he added: “ It was a more than successful broadcast. And the idea is precisely to continue advancing in this type of technique, because we are not exempt from having to use it in the future, given the concrete threat of an asteroid on a collision course with our planet.”
Other strategies, such as the use of nuclear explosives or evacuation of the impact zone, have also been evaluated if a collision is unavoidable.
ESA plans to launch the RAMSES probe in 2028 to study the asteroid Apophis as it approaches Earth in 2029. However, some experts have suggested that this mission could be rerouted to 2024 YR4 if the threat persists.
Constant monitoring and international cooperation
The International Asteroid Warning Network, NASA, and ESA continue to collect data to refine predictions about the trajectory of 2024 YR4. “ It’s a rare event ,” said IAWN representative Tim Spahr , noting that it’s unusual for an asteroid to exceed the 1% impact probability threshold.
Meanwhile, Paul Chodas, director of NASA’s Center for Near-Earth Object Studies, expressed his reassurance regarding the current situation. ” We are not concerned about asteroid 2024 YR4, as the probability of it not impacting is 99% ,” he explained. However, he insisted that monitoring will continue to ensure safety.
As new observations become available, the impact probability will likely be reduced, and the asteroid will be reclassified to level 0 on the Torino scale, indicating that it poses no risk to Earth.
The case of 2024 YR4 is a reminder of the importance of astronomical surveillance and international cooperation in planetary defense . Asteroid impacts, although rare, are the only natural disasters that can be prevented well in advance.
Current technology allows for the detection, monitoring, and, in some cases, mitigation of space-borne threats. The challenge lies in coordinating efforts globally and ensuring that the necessary resources are available when needed.
As the experts concluded, “These events are an opportunity to unite the international community against a truly common enemy.”
