Departing sunspot complex AR2565-AR2567 erupted on July 23rd, twice, producing two strong solar flares in quick succession. The first registered M5 on the Richter Scale of Flares. The second registered M7.6, making it the strongest flare of 2016 so far.
Radiation from the two flares ionized the top of Earth's atmosphere, causing a blackout of shortwave radio transmissions over the Pacific side of Earth. People who might have noticed the blackouts include ham radio operators, mariners and aviators.