Most Dangerous Asteroid in the Last 20 Years: Will 2024 YR4 Hit Earth?
Lately, the news of asteroid 2024 YR4 predicted to hit Earth has blasted the Internet. No wonder: it has become one of the most dangerous near-Earth objects in the last 20 years. Its size and record-high probability of collision with Earth make it a significant threat to monitor closely. Let's see what is known about this asteroid so far, why it's considered dangerous, and how high the probability of a collision is. By the way, with the help of the Sky Tonight app you can easily find out where it is flying by now: although you won’t see the asteroid, it’s still rather thrilling to track it, especially after all the news.
Contents
- Asteroid 2024 YR4: potential impactor
- Asteroid 2024 YR4 hitting Earth: odds & possible effects
- Asteroid 2024 YR4: what’s next?
- Asteroid 2024 YR4: to sum up
Asteroid 2024 YR4: potential impactor
Asteroid 2024 YR4 was discovered by the ATLAS telescope on December 27, 2024 – right after its close approach to Earth: two days earlier, the asteroid passed at a distance of 830,000 kilometers (about 2.15 times the distance to the Moon) from our planet. It completes an orbit around the Sun in about 4 years.
For now, asteroid 2024 YR4 is 43 million kilometers from Earth and continues to move away. However, its orbit will eventually bring it back closer to our planet—potentially too close to pass unnoticed. Calculations suggest that asteroid 2024 YR4 has a chance of hitting Earth on December 22, 2032 – just 8 years from now. Of the six possible impact dates calculated for this asteroid, this one is the closest in time and carries the greatest risk.
How big is asteroid 2024 YR4?
2024 YR4 is estimated to be 44-100 meters in diameter, which is similar in size to a Boeing 737 aircraft (on the smaller end) and Big Ben or Statue of Liberty (on the larger end). It can also be compared with the Tunguska impactor – an estimated 50-meter asteroid that flattened 2,000 square kilometers of Siberian forest back in 1908.
How dangerous is asteroid 2024 YR4?
Asteroid 2024 YR4 scored 3 of 10 points on the Torino scale, which means it has a 1% (or higher) chance to hit the Earth in less than 10 years and cause local damage, and therefore, demands the attention of astronomers and the public. For now, it is the only member of NASA’s and ESA’s risk lists with a Torino ranking that high (all other tracked objects have a ranking of 0). This is a new record since Apophis, which had 4 points in 2004.
Since the risks are extraordinarily high, the International Asteroid Warning Network (IAWN) issued a Potential Asteroid Impact Notification on January 29, 2025. This notification is part of IAWN’s protocol to alert the public and space agencies about an asteroid’s potential to collide with Earth, allowing time for further observation, risk assessment, and possible mitigation planning.
Asteroid 2024 YR4 hitting Earth: odds & possible effects
Let's take a closer look at the possible outcome of asteroid 2024 YR4 hitting Earth, and how much is 1% for an asteroid impact probability.
Where could asteroid 2024 YR4 hit?
According to the statement issued by the International Asteroid Warning Network (IAWN), the potential impact risk corridor stretches across the eastern Pacific Ocean, northern South America, the Atlantic Ocean, Africa, the Arabian Sea, and South Asia. This means that the impact could affect densely populated regions such as India, Pakistan, Bangladesh, Nigeria, Sudan, Ethiopia, Ecuador, Colombia, and Venezuela.
What happens if asteroid 2024 YR4 hits Earth?
The outcome of the impact can vary depending on three things:
- Size;
- Composition;
- Impact location.
Size: how big could the blast be?
- If we assume that its actual diameter is about 50 meters (which is close to the lowest estimates), the impact energy would be about 8 megatons of TNT. The resulting blast could be 16 times stronger than the Chelyabinsk event, when the shockwave blew out windows in 7,000 buildings, and 1,500 people were injured.
- If we take as true the largest estimates, namely a diameter of 100 meters, the impact energy would be 50 megatons of TNT, which is roughly equivalent to a nuclear bomb explosion (one Tsar Bomba or 3,333 Little Boys). Check our infographics about dangerous asteroids to further explore the connection between an asteroid’s size and the possible impact effects.
Composition: will it explode or make a crater?
- If asteroid 2024 YR4 is made of rock, it might blow up in the sky, causing a big explosion and a fireball that hits the ground.
- If it’s composed of iron, it would go through the atmosphere easily and hit the ground, making a crater.
Impact zones: what’s at risk?
- One of the most likely impact scenarios involves the asteroid falling into the ocean (Pacific, Atlantic, or Arabian Sea). A shallow-water impact could trigger a tsunami tens of meters high, severely affecting coastal cities. A deep-ocean impact would generate smaller waves but could still disrupt global shipping.
- If the impact affects an urban area (a major city such as Mumbai, Lagos, or Bogota), the shockwave would likely demolish buildings within a 10-30 kilometer radius, resulting in hundreds of thousands to millions of casualties in densely populated regions.
- If it lands far from the big cities, the environmental impact would still be significant. The explosion could trigger forest fires, and shockwaves would be felt hundreds of kilometers away.
As you can see, asteroid 2024 YR4 won’t pose a mass-extinction-level threat in either case. However, local damage would be devastating.
What are the chances of asteroid 2024 YR4 hitting Earth?
Estimates given by astronomers all over the world vary from 0.5% to 6%, depending on the calculation method. That doesn’t seem like much, but usually, risks are much smaller than that: most near-Earth asteroids have impact probabilities in the range of 0.00001% or less. In addition, the probability of collision decreases or gets ruled out after further observations. But for now, the risk seems to keep growing. Over January 2025, the estimate provided by ESA has risen from 0.99% to 1.32%. NASA currently rates the probability of a collision at 1.4%.
Since observations take time, it's too early for definitive conclusions. Perhaps later, asteroid 2024 YR4 will turn out to be safe for Earth, as has been the case with many asteroids heading toward Earth before – we discuss them in more detail in our article on dangerous asteroids. By the way, there, we calculate the chances of dying as a result of an asteroid impact and analyze ways to protect the Earth from asteroids – a very relevant and uplifting read.
Asteroid 2024 YR4: what’s next?
Since the impact probability is higher than ever and the asteroid is large enough to cause significant damage, the two UN-endorsed asteroid reaction groups – the International Asteroid Warning Network (IAWN) and the Space Mission Planning Advisory Group (SMPAG) – were activated to address the issue. Together, they will keep observing the asteroid and develop further strategies, up to spacecraft-based deflection missions.
Asteroid 2024 YR4 will be observable through early April 2025. Hopefully, by that time, the impact risk will be eliminated, but there’s a chance the asteroid will fade from view before that. In this case, it will be considered dangerous until it becomes visible again by the end of 2028. Through the beginning of 2029, astronomers will be able to see it through telescopes to refine the trajectory considerably. By that time, the countdown to impact will be about four years. Hopefully, this will be enough to devise and implement defensive methods (or, better yet, eliminate the possibility of needing them).
Asteroid 2024 YR4: to sum up
Asteroid 2024 YR4 is a newly discovered asteroid that has a 1% chance of colliding with the Earth on December 22, 2032. With an estimated size of 44-100 meters, an impact could cause significant local damage, potentially destroying a city. As the risk is considered unusually high, it has drawn the attention of both scientists and the general public. While current risk estimates are rising, additional observations will likely clarify – and potentially dismiss – the threat.
