New Zealanders may see auroras light up the sky tonight after a huge solar flare - described by scientists as being in the largest category, or "X-class" - erupted on the Sun yesterday morning.
The solar storm is due to arrive today, and forecasters at the US government's Space Weather Prediction Center expect minimal impact to communication systems and power grids.
It may also spark colourful auroras in the far south of New Zealand and in Canada and the United States.
Mt John University Observatory astronomer Alan Gilmore said it normally takes 24 to 36 hours to see auroras following a solar flare.
"It's worth having a look tomorrow (Saturday) night," he said.
Nasa reports the radiation is moving towards Earth at a speed of about 1368km per second.
X-class is the grading given to the biggest flares the sun emits.
The storm is part of the sun's normal 11-year cycle, which is expected to reach a peak next year.