World warned most powerful Sun storm in 20 years to hit on Friday

Authorities in America have issued the first Severe (G4) Geomagnetic Storm Watch alert in almost 20 years as a powerful solar storm will hit the Earth on Friday. The National Oceanic and Atmospheric Administration (NOAA) issued the alert late on Thursday, the first alert of this level since 2005.

In January 2005 the Earth was hit by the highest levels of solar radiation in 50 years. Today's storm could be powerful enough to disrupt power grids, GPS satellites and some communications.

The electromagnetic storm will collide with the Earth's atmosphere after solar storms on the surface of the Sun earlier this week. They could bring spectacular Northern lights displays and possible disruption of everything from GPS to the Internet.

The alert reads: "NOAA's Space Weather Prediction Center (SWPC)- a division of the National Weather Service - is monitoring the sun following a series of solar flares and coronal mass ejections that began on May 8. Space weather forecasters have issued a Severe (G4) Geomagnetic Storm Watch for the evening of Friday.

"Additional solar eruptions could cause geomagnetic storm conditions to persist through the weekend. A large sunspot cluster has produced several moderate to strong solar flares since Wednesday at 5:00 am ET. At least five flares were associated with Coronal Mass Ejections that appear to be Earth-directed. SWPC forecasters will monitor NOAA and NASA's space assets for the onset of a geomagnetic storm."

Coronal Mass Ejections are explosions of plasma and magnetic fields from the sun's surface.

The warning added: "Geomagnetic storms can impact infrastructure in near-Earth orbit and on Earth's surface," and said it could "potentially [disrupt] communications, the electric power grid, navigation, radio and satellite operations."

The severe storm watch will be in place until Sunday night. The alert reads: "SWPC has notified the operators of these systems so they can take protective action,' officials wrote upon administering the action. Geomagnetic storms can also trigger spectacular displays of aurora on Earth."

People across the Uk could see Northern Lights this weekend.