The coronal mass ejection that erupted from the sun on Oct. 4, 2012 at 11:24 p.m. EDT arrived at Earth on Oct. 8 at 12:30 a.m. EDT, as observed by instruments aboard NASA’s Advanced Composition Explorer (ACE) spacecraft. At Earth, when the CME connected up with Earth’s magnetic environment, the magnetosphere, it caused a space weather phenomenon called a geomagnetic storm. This storm was categorized by NOAA as a G2 – on a scale from G1 to G5. A storm at this level is considered reasonably mild. Auroras did appear in the north, including Canada, due to this storm.
This is a copy of the full report by NASA
