All Things Space, UFOs, etc.2 ‘intense’ solar flares in just 7 hours, the strongest in months, knock out radio signals on Earth: NASA Posted on May 19, 2026 by Administrator Talk about a heated situation. The sun unleashed two colossal solar flares within seven hours of each other this week, triggering radio blackouts across parts of Earth. Solar flares are strong, powerful explosions of energy that have the potential to wreak havoc on radio communications, electric power grids and navigation signals — and can pose potential risks to spacecraft and astronauts.