Storm Spotting; March 2004; Scientific American Magazine; by Krista West; 3 Page(s)

On October 19, 2003, a large solar flare erupted from the surface of the sun, drawing scientists' attention to three massive sunspot groups that, over the next two weeks, produced a total of 124 flares. Three of them were the biggest flares ever recorded. Along with these bursts of electromagnetic radiation came enormous clouds of plasma mixed with magnetic fields. Known as coronal mass ejections (CMEs), these unpredictable clouds consist of billions of tons of energetic protons and electrons. When directed earthward, CMEs can create problems. At last count, the fall's flares and CMEs affected more than 20 satellites and spacecraft (not including classified military instruments), prompted the Federal Aviation Administration to issue a first-ever alert of excessive radiation exposure for air travelers, and temporarily knocked out power grids in Sweden.

Historically, CMEs have struck the earth with little or vague warning. If they could be forecast accurately, like tomorrow's weather, then agencies would have time to prepare expensive instruments in orbit and on the ground for the correct size and moment of impact. Such precise predictions could soon emerge: last December researchers announced the early success of a forecasting instrument, called the Solar Mass Ejection Imager (SMEI), that can track CMEs through space and time.