Iron sulfide may be keeping Mercury’s core toasty and its magnetic field alive

New estimates of the core’s heat loss could explain the planet’s long-lived magnetic field

magnetic field lines

NASA’s MESSENGER spacecraft has detected magnetic signals in Mercury’s surface rocks, and even stronger ones in lower orbit. Red and orange in this image represent the direction of the field lines pointing off-planet, while blue and purple lines point inward.

NASA's Scientific Visualization Studio

Mercury’s core may be wearing a metal jacket.