An asteroid wiped out the dinosaurs 66 million years ago, raising questions about whether humanity faces a similar threat. While large impacts are rare, ongoing monitoring and technology offer ways to mitigate potential dangers. Experts emphasize preparation over worry for this distant risk.
The asteroid responsible for the extinction of dinosaurs 66 million years ago measured at least 10 kilometres across, triggering megatsunamis, widespread forest fires, and global sky darkening. Such massive impacts occur approximately every 60 million years, according to Earth's crater record. Smaller asteroids, around 1 kilometre in diameter, strike about every million years, with the most recent event roughly 900,000 years ago.
Astronomers track thousands of near-Earth objects, identifying only about 35 with a greater than 1-in-a-million chance of impact in the next century. These are nearly all under 100 metres across and carry very low probabilities. Humanity's advantage lies in space observation: all potentially dangerous asteroids 10 kilometres or larger have been detected, providing reassurance against a dinosaur-scale catastrophe.
For 1-kilometre asteroids, detection covers about 80 percent, reducing surprises from this size. However, fewer than half of 100-metre 'city-killers'—capable of significant local damage—have been found. Smaller objects, like the 2013 Chelyabinsk meteor, typically burn up or cause minor harm.
Advancements include the upcoming NEO Surveyor telescope, set for launch next year, to enhance tracking. NASA's 2022 Double Asteroid Redirection Test successfully altered an asteroid's path, proving deflection is feasible with sufficient warning of at least a couple of years.
Should an impact occur, it would likely strike ocean or uninhabited land, as less than 15 percent of Earth's land—and under 4.3 percent of its surface—is human-modified. Response strategies mirror those for other natural disasters: evacuation, mitigation, and sheltering. Strengthening general disaster preparedness benefits multiple threats, while astronomers continue vigilant sky monitoring.