Earlier this week, the Sun released two large solar flares in quick succession. Associated coronal mass ejections headed close to Earth may still make direct hits. While skywatchers anticipated a high latitude auroral treat for the eyes, R3 radio blackouts occurred across half the planet, raising the questions: why do these radio blackouts occur, and how are they measured? The rest of this article is behind a paywall. Please sign in or subscribe to access the full content.

What causes radio blackouts?

Solar flares involve large, sometimes enormous, bursts of electromagnetic radiation. These briefly bump up the Sun’s usual output, and the energy released is much more concentrated at higher frequencies, including X-rays, than normal sunlight. The radiation reaches Earth in eight minutes

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