The bright flash in the upper right of the disk is called an arcade. Halo CMEs are the hardest to detect, but Crooker and her colleagues have identified the signature of halo CMEs on the sun's surface. Now, a fleet of ten space-based observatories run by an international team of space scientists are keeping an eye on the sun in the hopes of providing an early warning system for geomagnetic storms. From December 1996 to May 1997, the SOHO satellite successfully detected nine of twelve known space storms, vastly improving the forecast accuracy. With advance warning from reliable space weather forecasts, power companies, space-walking astronauts, and satellite operators can prepare for impact and minimize damage from CMEs.
Researchers say halo CMEs almost always lead to magnetic storms on earth.
This halo CME was imaged by the Lasco C3 instrument on the SOHO spacecraft.