April 22, 2021: Earth-facing sunspot AR2816 exploded on April 22nd (0435 UT), producing a C3.8-class solar flare. NASA’s Solar Dynamics Observatory recorded a dramatic shock wave rippling away from the blast site:
This is a “solar tsunami.” It is a wave of hot plasma and magnetism, about 100,000 km tall, racing outward at approximately 250 km/s (560,000 mph). Such waves are usually associated with the launch of coronal mass ejections (CMEs)–and indeed, one has been observed.
Coronagraphs onboard the Solar and Heliospheric Observatory (SOHO) detected a CME billowing away from the sun hours after the flare. It is faint but definitely Earth-directed:
The initial velocity of the CME was ~760 km/s. Based on its speed and other factors, NOAA forecasters believe that the CME will reach Earth on April 25th, potentially sparking G2-class geomagnetic storms. Aurora alerts: SMS Text.