The intensity of the aurora borealis after the biggest solar flare in six years swept across the night sky.
U.S. space weather experts from the National Oceanic and Atmospheric Administration said that so far they had heard of no problems from the storm that triggered the auroras.
However, some airline flights had to be re-routed away from the North Pole.
It was part of the strongest solar storm in years, but the sun is likely to get even more active in the next few months and years, said physicist Doug Biesecker at the U.S. Space Weather Prediction Center in Boulder, Colorado.
Physicists say we shouldn't worry about harmful radiation because the magnetic field around Earth is protecting us.
The Associated Press contributed to this report.