Once in Three Thousand Years
Jan. 21st, 2013 11:46 pmEarth experienced gamma ray burst in AD 774 or 775:
http://www.spacedaily.com/reports/Gamma-ray_burst_blasted_Earth_in_8th_century_study_999.html
http://www.spacedaily.com/reports/Gamma-ray_burst_blasted_Earth_in_8th_century_study_999.html