The Bastille Day Flare or Bastille Day Event was a powerful solar flare on July 14, 2000, occurring near the peak of the solar maximum in solar cycle 23. The X5.7-class flare originated from a sunspot known as Active region 9077, which subsequently caused an S3 radiation storm on Earth fifteen minutes later as energetic protons bombarded the ionosphere. It was the biggest solar radiation event since 1989. The proton event was four times more intense than any previously recorded since the launches of SOHO in 1995 and ACE in 1997. The flare was also followed by a full-halo coronal mass ejection and a geomagnetic super storm on July 15–16. The geomagnetic storm peaked at the extreme level, G5, in the late hours of July 15.
Despite their great distance from the Sun, the Bastille Day event was observed by Voyager 1 and Voyager 2.
^ Webber, W. R., F. B. McDonald, J. A. Lockwood, and B. Heikkila (2002), The effect of the July 14, 2000 "Bastille Day" solar flare event on >70 MeV galactic cosmic rays observed at V1 and V2 in the distant heliosphere, Geophys. Res. Lett., 29, 10, 1377-1380, doi:10.1029/2002GL014729.