What Are the Odds of a Catastrophic Asteroid Impact? A New Study Calculates the Risk
For as long as humans have looked up at the night sky, we’ve worried about what might fall down. The memory of the asteroid that wiped out the dinosaurs 66 million years ago is etched into our collective consciousness, fueling countless disaster movies and doomsday theories. But how likely is a similar event to happen during our lifetime? And what are the actual odds of an asteroid hitting Earth?
A recent study led by physicist Carrie Nugent of Olin College of Engineering has put some solid numbers behind this cosmic risk, providing a much-needed reality check by comparing the threat to other, more familiar causes of death. The findings were published in the Planetary Science Journal.
The Numbers Behind the Threat
Researchers focused their analysis on Near-Earth Objects (NEOs)—asteroids and comets that pass within 120 million miles of our planet. Specifically, they looked at NEOs with a diameter of more than 140 meters. An object of this size is large enough to cause widespread regional or even global devastation upon impact.
Using a sophisticated model, the team simulated the trajectories of five million of these objects over a 150-year period. Their findings revealed just three simulated impacts. This translates to an annual probability of 0.009% that a potentially destructive asteroid will strike Earth. To put it another way, a significant impact like this is likely to occur only once every 11,000 years, on average.
How Does This Compare to Other Risks?
While a one-in-11,000-year event seems incredibly rare, the study puts the number into perspective by comparing it to other unusual but preventable causes of death. In the United States, for example, the annual chance of death from:
- Lightning strike: 0.00034%
- Rabies: 0.000015%
- Carbon monoxide poisoning: 0.0019%
The study also considered highly improbable accidents, such as being buried alive while digging a deep hole in the sand—an event that causes about three deaths per year.
But when compared to more common occurrences, the numbers become clearer. In just one U.S. state, over 30,000 car accidents occur each year, causing 366 deaths. On a global scale, the flu infects around one billion people annually, leading to approximately 470,000 deaths.
The study’s most surprising takeaway is this: the cumulative chance of an asteroid over 140 meters hitting Earth somewhere during a person’s average lifespan of 71 years is around 0.64%, which is less than 1% but still higher than the odds of being struck by lightning.
It’s also far more likely that you would die in a car accident or from the flu than from a global asteroid impact. However, while the probability of an impact is low, the consequences could be catastrophic. While an asteroid might fall harmlessly into the ocean, a strike on a populated area could affect up to a million people.
The Future of Planetary Defense
The research also touched on the importance of planetary defense efforts. In 2022, NASA’s DART mission successfully demonstrated that it is possible to alter an asteroid’s trajectory by intentionally crashing a spacecraft into it. This is considered a crucial step toward “buying insurance against a global disaster,” as the study authors put it.
While asteroid threats are now well-documented, the study notes that less-understood risks, such as long-period comets and interstellar objects, also exist. Comets, for example, can travel at three times the speed of asteroids, making them much harder to track and defend against.
Ultimately, the study’s conclusion is clear: the risk of an asteroid impact is low, but it’s not zero, and it’s higher than many people imagine.
Adapted from SuperInteressante
