The powerful explosions that rock highly magnetic neutrons stars called magnetars (as imagined in this rendering) come from just beneath their surface, according to a new study. Researchers modeled the burst of X-rays from a 2003 explosion of the magnetar XTE J1810-197 to identify its source. Their model also pegged the magnetar's magnetic field at 600 million million times stronger than Earth's, despite being roughly the size of a mountain, they report in a paper to appear in The Astrophysical Journal.