A colossal explosion in the sky, an eruption of energy hundreds of times greater than the Hiroshima bomb. A blinding flash nearly as bright as the sun. Shockwaves powerful enough to flatten everything for miles. This may sound like something straight out of an apocalyptic movie, but it’s a reality that scientists are closely monitoring.
A newly detected asteroid, 2024 YR4, now has a greater than one percent chance of colliding with Earth in approximately eight years. While the threat is real, it is far from certain. However, if this asteroid were to impact, it could lead to city-level devastation, depending on where it strikes. While no one is sounding the alarm yet, scientists are taking this threat very seriously and keeping a watchful eye on its trajectory.
“We are paying close attention, and we’re getting as many assets as possible to track it,” said Bruce Betts, the chief scientist of The Planetary Society.
A Rare and Dangerous Find
The asteroid 2024 YR4 was first observed on December 27, 2024, by the El Sauce Observatory in Chile. Based on its brightness, astronomers estimate that it is between 130 and 300 feet (approximately 40-90 meters) wide, nearly the size of a football field. By New Year’s Eve, the object had been flagged as a potential concern and was swiftly put on the radar of Kelly Fast, the acting planetary defense officer at NASA.
Fast noted that while asteroid observations often appear and then fade away, 2024 YR4 seemed like it could persist in its path. “You get observations, they drop off again. This one looked like it had the potential to stick around,” she said.
As further observations were made, the asteroid’s risk assessment climbed steadily. On January 29, 2025, the International Asteroid Warning Network (IAWN), a global planetary defense collaboration, issued a memo stating that there is now a 1.6 percent chance of a collision on December 22, 2032.
Possible Impact Zones
If 2024 YR4 were to strike Earth, potential impact zones include the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and South Asia, according to the IAWN. The asteroid follows a highly elliptical orbit that takes it past the inner planets before swinging out toward Jupiter, meaning that its path brings it into close proximity with Earth on certain occasions.
As of now, 2024 YR4 is moving away from Earth, and its next close pass will not happen until 2028. The probability of a collision is still considered low, and many experts, including Bruce Betts, believe that as more observations are made in the coming months and years, the likelihood of an impact will diminish significantly. “The odds are very good that not only will this not hit Earth, but at some point in the next months to few years, that probability will go to zero,” Betts said.
This scenario is reminiscent of the 2004 discovery of Apophis, an asteroid that initially had a 2.7 percent chance of colliding with Earth in 2029. Subsequent observations ultimately ruled out the impact, underscoring that these types of predictions are often refined over time.
The Potential Destruction: “City Killer” Category
The most famous asteroid impact in history occurred about 66 million years ago, when a massive asteroid, approximately six miles wide, collided with Earth. This catastrophic event triggered a global winter, wiping out the dinosaurs and 75 percent of all species. Fortunately, 2024 YR4 is much smaller and would likely cause far less damage than the dinosaur-extinction-level event.
However, it still poses a serious threat to humanity, particularly if it were to strike in a populated region. 2024 YR4 falls into what is known as the “city killer” category. If the asteroid were to hit a major city like Paris, London, or New York, the destruction would be catastrophic, essentially wiping out the entire city and its surrounding areas.
In terms of scale, the best modern comparison is the 1908 Tunguska Event, which saw an asteroid or comet fragment measuring between 30 and 50 meters explode in the sky above Siberia, flattening 80 million trees across 770 square miles (around 2,000 square kilometers). Like the Tunguska event, 2024 YR4 would likely explode in the atmosphere, creating an airburst rather than leaving a massive crater on the ground.
Unimaginable Energy Release
To better understand the scale of the potential destruction, scientists can calculate the energy released by such an impact. Andrew Rivkin, a planetary astronomer at the Johns Hopkins Applied Physics Laboratory, explained that the explosion from an asteroid like 2024 YR4 would be equivalent to around eight megatons of TNT—more than 500 times the power of the atomic bomb dropped on Hiroshima during World War II.
If 2024 YR4 were to explode over the ocean, the immediate damage would likely be less severe, but there would still be concerns about triggering a tsunami, especially if the asteroid impacted near a coastline. This could result in catastrophic consequences for coastal communities, depending on the size of the wave and the proximity of the impact site.
The Good News: We Have Time
Despite the potential danger, experts stress that we have plenty of time to prepare. The real breakthrough came in 2022, when NASA successfully tested a new planetary defense method using the DART mission (Double Asteroid Redirection Test). In this mission, a spacecraft successfully nudged an asteroid off its course using a technique known as the kinetic impactor method. Rivkin, who led the investigation for NASA’s DART mission, believes that the same technique could work for 2024 YR4, assuming that the asteroid’s trajectory and size are conducive to such a strategy.
“I don’t see why it wouldn’t work,” Rivkin said, referring to the potential of the kinetic impactor method. However, the larger challenge may be getting countries to fund such a mission if their own territory isn’t directly threatened.
Other innovative ideas for planetary defense also exist. For example, lasers could be used to vaporize part of the asteroid, creating a thrust effect that would push it off course. Another concept involves using a gravity tractor, a large spacecraft that could gently tug on the asteroid using its own gravitational pull. Although these methods are still theoretical, they offer hope for diverting potentially dangerous objects from Earth.
In the worst-case scenario, the long warning time gives authorities the opportunity to evacuate potential impact zones, ensuring that the risk to human life is minimized.
What Should We Do?
While 2024 YR4 presents a real threat, Kelly Fast from NASA offers reassurance: “Nobody should be scared about this. We can find these things, make these predictions, and have the ability to plan.” The ability to detect and track asteroids gives scientists a valuable tool in planetary defense, and thanks to advancements in technology, we now have the capability to prevent potential disasters before they happen.
The continued monitoring of 2024 YR4 will be crucial, as more data will help scientists refine their predictions and, if necessary, prepare for any potential threats. As we’ve seen with previous asteroid threats, time is often our greatest ally.
For now, while it’s wise to stay informed and vigilant, there’s no need to panic. Thanks to the work of astronomers, scientists, and planetary defense experts, humanity is in a better position than ever to respond to potential asteroid threats.