Solar Minimum Sunspot During the past 24 hours, sunspot AR2715 has almost quadrupled in size, growing two dark cores larger than Earth. The active region is now crackling with low-level solar flares such as this C2-class explosion recorded by NASA's Solar Dynamics Observatory at 01:15 UT on June 21st. A pulse of extreme ultraviolet radiation from the flare briefly ionized the top of Earth's atmosphere above the Pacific Ocean (map), causing a shortwave radio brownout at frequencies below 10 MHz.

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