2004 magnetar flare delivered Sun-scale energy to Earth in 0.2 seconds

A December 27, 2004 giant flare from magnetar SGR 1806-20, though tens of thousands of light-years away, saturated satellites and briefly disturbed Earth’s ionosphere. In the first 0.2 seconds the flare released energy comparable to the Sun’s output over about 250,000 years. Follow-up observations showed a pulsating tail tied to the magnetar’s rotation, with distance estimates later revised, complicating exact energy figures. The event also illustrated how a Galactic magnetar flare can resemble a short gamma-ray burst if viewed from afar, but it posed no danger to Earth and remains a key, well-documented case for magnetar physics and energy release mechanisms.