
A powerful solar storm hit Earth on April 23 at 1:37 p.m. EDT (1737 GMT) and sparked magnificent aurora shows around the world.
Geomagnetic storms are disturbances to Earth's magnetic field caused by solar material from coronal mass ejections (CME) — large expulsions of plasma and magnetic field from the sun's atmosphere. This particular geomagnetic storm was triggered by a CME which left the sun on April 21.