Yesterday, that same sunspot emitted an M-class solar flare — one-tenth the size of an X-class flare — leading to a coronal mass ejection aimed toward Earth that could cause auroras tonight as far south as Ohio and Indiana.
CME from these latest flares could lead to even more spectacular auroras, but could also damage satellites, communications and power systems. That cloud of charged plasma would arrive within 1 to 3 or 4 days, Steenburgh said, although CMEs triggered by energetic flares generally come quickly.
https://www.space.com/38057-sun-unleashes-decades-strongest-solar-flare.html
Sun Unleashes Monster Solar Flare, Strongest in a Decade
By Sarah Lewin, Space.com Associate Editor | September 6, 2017 05:55pm ET
Many readers are asking about the historic context of this event. How epic is it? Answer: This is a decade-class flare. A list of the most powerful solar flares recorded since 1976 ranks today’s flare at #14, tied with a similar explosion in 1990. However, compared to the iconic Carrington Event of 1859, or even the more recent Halloween storms of 2003, this event is relatively mild. Modern power grids, telecommunications, and other sun sensitive technologies should weather the storm with little difficulty.
On the other hand, sky watchers could see some fantastic auroras before the week is over. And ham radio operators will surely be noticing strange propagation effects as the sun exerts its influence on our planet’s ionosphere. Stay tuned for updates.