A pair of scorching explosions on the Sun's surface is sparking the biggest radiation and geomagnetic storm the Earth has experienced in five years, space weather experts said Wednesday. The storm, expected to hit Earth early Thursday US time and last through Friday, may disrupt power grids, GPS systems and satellites, and has already forced some airlines to change their routes around the polar regions. In addition to possibly garbling some of Earthlings' most prized gadgets, the event will likely give nighttime viewers in parts of Central Asia a prime look at the aurora borealis, or northern lights, on Thursday night. "Space weather has gotten very interesting over the past 24 hours," said Joseph Kunches, a space weather scientist with the National Oceanic and Atmospheric Administration (NOAA). The fuss began late Sunday at an active region on the Sun known as 1429, with a big solar flare that was associated with a burst of solar wind and plasma known as a coronal mass ejection that hurtled in Earth's direction at some four million miles per hour (6.4 million kilometers per hour).