The Planet-Killer

Could an Asteroid Destroy Civilisation? The Real Planet-Killer Risk — and the Objects Scientists Are Watching There is a natural disaster capable of dwarfing almost anything humanity has experienced in recorded history. No government could stop its immediate effects, national borders would become irrelevant and, at sufficient scale, the climate itself could change. A large asteroid striking Earth could theoretically collapse modern civilisation — and an object several miles across could trigger a mass extinction. But that does not mean a planet-killing asteroid is currently heading towards us. As of September 2026, astronomers know of no large asteroid with a significant probability of striking Earth within the next century, and more than 90 per cent of the near-Earth asteroid population roughly one kilometre or larger has already been discovered. The more interesting question is therefore not whether asteroid impacts can destroy civilisation. They can. It is how big the object would need to be, how likely such an event really is, which known asteroids carry the greatest calculated risk, and whether the object humanity ultimately needs to fear could still be undiscovered.