The sun emitted two significant X-class flares on September 6, 2017 from NOAA AR 12673. The second X9.3 class flare was most powerful in more than a decade. At 09:10 UT, an X-class solar flare — the most powerful sun-storm category — blasted from a large sunspot on the sun's surface, was the strongest since 2015, at X2.2, but it was dwarfed just 3 hours later, at 12:02 UT, by an X9.3 flare. X-class solar flares can cause radiation storms in Earth's upper atmosphere and trigger radio blackouts. The debris from monster X9-class solar flare reached Earth and severe G4-class geomagnetic storm.