ESA - The biggest solar X-ray flare ever is classified as X28

It has been announced that the massive solar X-ray flare which occurred on 4 November was, at best estimate, an X28. There is still a small chance this will be revised by a small amount, but it is now official: We have a new number 1 X-ray flare for the record books, the most powerful in recorded observational history.

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Has there ever been an X10 solar flare? - Quora

Solar flare National Aeronautics and Space Administration Wiki

The Largest Solar Flare Of The Space Age (Credits: Dr. C. Alex

The Sun released an X-class solar flare, the largest

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