The Digester

A civilization-ending asteroid is extremely unlikely in our lifetime, but gaps remain for 100 metre class objects; better telescopes and demonstrated deflection technology reduce the risk further.

Extinction level impacts from 10 kilometre asteroids are extremely rare and all such potential threats have been found.
Kilometre-scale impacts happen about once per million years and roughly 80 percent of those asteroids have been detected.
Objects smaller than 100 metres usually burn up or cause only local damage, like the 2013 Chelyabinsk event.
Asteroids around 100 metres across can cause city-scale destruction and less than half of them have been discovered.
Astronomers track thousands of near-Earth objects and only about 35 have more than a one-in-a-million chance of hitting Earth in the next 100 years.
NASA's DART mission showed we can alter an asteroid's path if we detect it years in advance, and the NEO Surveyor telescope launching next year should find many more hazardous objects.
If an impact were unavoidable it would likely hit the ocean or uninhabited land, and response would follow ordinary disaster planning such as evacuation and sheltering.

How worried should you be about an asteroid hitting Earth?

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