Of the millions of asteroids floating around the Solar System, what makes some of them risky? Julia de Leon, Researcher at the Instituto de Astrofísica de Canarias, defines 'Potentially Hazardous Asteroids'.
Asteroids can tell us about the origins of the Solar System and maybe even life itself, but they also pose a risk to Earth as many graze past our planet on a regular basis. Find out more about what ESA is doing to protect us through its Planetary Defence Office, part of the Space Safety programme.