A solar flare is a violent explosion in a star's atmosphere releasing up to a total energy of 6×1025 Joules. Solar flares take place in a star's corona and chromosphere, heating plasma to tens of millions of kelvins and accelerating electrons, protons and heavier ions to near the speed of light. They produce electromagnetic radiation across the spectrum at all wavelengths from long-wave radio to the shortest wavelength gamma rays. Most flares occur in active regions around sunspots, where intense magnetic fields emerge from a star's surface into the corona. Flares are powered by the sudden release of magnetic energy stored in a star's corona.
If a Stargate's matter stream passes by a star when a solar flare is occurring, the matter being transmitted through it can be propelled either forward or backward in time. (SG1: "1969", "2010", "Continuum", "SGA", "The Last Man", "SGU", "Time")
The cover story for the destruction of Apophis' fleet in orbit of Earth in 1998 was massive solar flare activity. In 2004, Joe Spencer attempted to use these reports to prove to his estranged wife Charlene Spencer that his visions about SG-1 were real. (SG1: "Citizen Joe")
When Destiny tried to dial Earth from inside a star in 2011, the combination of the dialing and a solar flare created a temporal event that threw Destiny twelve hours back in time. A second solar flare threw everyone except Dr. Nicholas Rush (who remained on Destiny) and Colonel David Telford (who returned to Earth) back in time 2,000 years. (SGU: "Twin Destinies", "Common Descent", "Epilogue")