End Times

How to Defend the Planet

A six-mile-wide asteroid ended the dinosaurs, and the same could happen to us one day. But NASA is at work on ways to keep us safe.

An illustration of an asteroid in space. Image credit: NASA / JPL / Caltech.

Asteroids, supervolcanoes, nuclear war, climate change, engineered viruses, artificial intelligence, and even aliens — the end may be closer than you think. For