Early Wednesday morning, the sun unleashed two monster solar flares (from those spots on the sun), the second of which was the most powerful we’ve seen in more than a decade. The burst of radiation was so intense, it caused high-frequency radio blackouts across the daytime side of Earth that lasted for about an hour. Sky-watchers, particularly those in high-latitude regions, should be on the lookout for auroras visible in the northern skies over the course of this week and into the weekend — but only if the smoke clears… Photos: left K. Leclair (Merritt), right NASA