The BBC story tells also the right distance from which the starquake on the magnetar could have harmed Earth, 10 lightyears. A supernova, the end of a massive star in an explosion - the kind of which the magnetar, a type of pulsar, was itself born - could sterilize Earth from a distance of at least 30 lightyears and could cause a mass extinction at least from a distance of a 100 lightyears. A gamma-ray burst could sterilize planets thousands of lightyears away.