Space weather experts say powerful solar flares over the next few days could disrupt communications satellites, GPS and shortwave radio around the world.

The solar outbursts, or coronal mass ejections, are expulsions of plasma and magnetic field from the outermost part of the sun's atmosphere.

The US National Oceanic and Atmospheric Administration said the flares are causing a severe geomagnetic storm that could last through the weekend. It issued its second-highest advisory for such storms.

Japan's National Institute of Information and Communications Technology says the flares are unlikely to impact cellular phone services. But it warns that GPS and certain types of radio communications could be affected in the coming days.

One effect of the flares is that the Northern Lights can be seen at lower latitudes than usual. People around the world have been taking pictures of auroras in their regions.