A powerful solar storm struck Earth, triggering spectacular celestial light shows in skies around the world — and threatening possible disruptions to satellites and power grids.

Scientists have updated their forecast for the current solar cycle, which usually lasts about 11 years. Solar activity is now expected to peak earlier and to be stronger than previously thought.

The Northern Lights, known scientifically as auroras borealis, are triggered by geomagnetic activity from the sun. They typically occur closer to the North Pole, near Alaska and Canada.