If, Not When It Happens: A History of Asteroid Impacts
Why We Plan for the Worst
Planetary defense is risk management on a cosmic scale. While asteroid impacts are rare, they’re not theoretical and they’ve left lasting scars across history, from the extinction of the dinosaurs to modern-day near-misses. Understanding the scale of past events and the science of what’s circling above today helps bring focus to the reality we face: It’s not about fear. It’s about being ready.
This article maps out significant asteroid events, both Earth-bound and in our galactic neighborhood, to provide a grounded perspective.
Historical Impact Events That Shaped the Conversation
66 Million Years Ago – Chicxulub Crater, Mexico
Believed to be the impact that ended the age of dinosaurs, it created a crater over 90 miles wide and triggered a global extinction event.1908 – Tunguska Event, Russia
A massive explosion leveled 800 square miles of Siberian forest. No crater was found, leading scientists to believe the object exploded in the atmosphere. Estimated at 3 to 5 megatons, it was 1000 times more powerful than the Hiroshima bomb.1994 – Comet Shoemaker-Levy 9 Hits Jupiter
A broken-up comet slammed into Jupiter with the force of 6 million megatons, larger than Earth’s entire nuclear arsenal. We watched it happen. Had that object hit Earth, it would have been extinction-level.2013 – Chelyabinsk, Russia
An asteroid the size of a house entered Earth’s atmosphere undetected, exploded mid-air, and injured over 1,600 people from shockwaves. Interestingly, astronomers were tracking a different asteroid that day. This one came from the direction of the sun, making it invisible until it entered Earth’s atmosphere. It’s a powerful reminder: angle matters.2029 – Apophis Flyby
This 1,100-foot asteroid is currently calculated to pass between Earth and our satellites in April 2029, closer than the Moon. It’s not expected to hit, but it’s a key focus for planetary defense exercises and observation.2032 – 2024 YR4 Returns
This asteroid was initially assessed with a high probability of Earth impact, estimated at over 70%. It triggered immediate international monitoring and scenario planning. By February 2025, updated models confirmed it would likely miss Earth but may pass close to the Moon.
Behind the Headlines: Global Coordination in Action
Following the Chelyabinsk incident in 2013, FEMA hosted a meeting with the Russian Academy of Sciences and their national emergency agency. It was the first time we heard firsthand how another country managed a real asteroid impact on their soil.
These meetings laid the groundwork for ongoing collaboration between U.S. agencies like NASA and FEMA, and their global counterparts. It’s part of a growing recognition that asteroid threats are a shared risk and require a shared response.
It was a unique experience, similar to some interactions I had as the first US Navy Officer assigned to the Peacekeeping Dept. at the UN. It was interesting that the response from our Russian counterparts would in some ways be the same as our and in other ways not. When discussing these scenarios with my international colleagues, national difference on how they would respond to a crisis can be evident. In the U.S. we have a standard National Response Framework, which makes national coordination for a large scale event not as challenging. While there are international protocols for responding to international disasters, an asteroid impact depending on the size could be overwhelming. We want to discuss what to do in this rare but potentially global catastrophic event ahead of time.
Putting It All Into Perspective
We tend to assume if something hasn’t happened in our lifetime, it won’t. But that logic doesn’t hold when the stakes are planetary. The truth is:
We’ve seen impacts large enough to reset life on Earth
We’ve watched them impact other planets
We’ve experienced modern-day events that have caused real damage
And we’ve narrowly missed close calls, even within our atmosphere
Planning is about perspective and protecting the future from threats that don’t announce themselves with fanfare.
There’s no need for fear, but we should be ready.