A solar flare of extraordinary intensity erupted from Active Region 10486 at 19:29 UTC on November 4, 2003, overwhelming every X-ray detector in orbit and leaving scientists temporarily blind to its true scale. Only later would they learn it reached about X45 — the most powerful ever measured in the Space Age. Its radiative power rivaled that of the 1859 Carrington Event, yet most of its debris was ejected harmlessly sideways into space. Had Active Region 10486 faced Earth, researchers estimate the geomagnetic index Dst could have dropped below –850 nanoteslas — enough to trigger a planetary-scale power-grid collapse.