Incoming radiation storms NASA/SDO

The sun is having an explosive day. On the morning of 6 September, an active region on the sun belched out two huge streams of radiation. One of them was the largest such flare in over a decade.

These two flares were both placed in the X-class, the most powerful type of solar flare. The larger of the two was classified as X9.3, the strongest since an X17 flare in 2005.

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X-class solar flares are the largest explosions in the solar system, often accompanied by twisting ropes of plasma ten times the size of Earth that curl up off the sun’s surface.


The most powerful solar flare ever detected occurred in 2003. It overloaded all of NASA’s solar measurement sensors, which cut out after measuring a flare of X28.

If, like these bursts, a solar flare is directed at Earth, it can create long-lived radiation storms that can wipe out some radio and GPS signals, interfere with satellites, and even damage electrical grids on the ground. In a few days, it could also lead to spectacular auroras.

This morning, high frequency radios stopped working on the side of Earth facing the sun and GPS communications were degraded for about an hour.

We have corrected the date of the most recent large solar flare.