Skywatchers marvel at light show

The light show as seen by a satellite above the Earth

By BBC News Online science editor Dr David Whitehouse

Skies across Europe and North America have been lit up with a spectacular display of the Northern Lights.

Scientists got an indication that a display of the Aurorae Borealis was possible when the ACE spacecraft, located approximately 1.6 million km (one million miles) towards the Sun, detected the passage of a fast-moving cloud of magnetically charged gas on its way to the Earth.

The curtains of light can be spectacular

The interplanetary shock wave passed ACE at about 1630 GMT on 6 April. Abruptly the speed of the solar wind increased from 375 km per sec (233 miles per sec) to nearly 600 km per sec (372 miles per sec). Such disturbances usually arrive at Earth about one hour after they pass ACE. Scientists issued an auroral alert.

Fast moving clouds of electrons from the Sun were funnelled towards the polar regions by the Earth's magnetic field. As they collided with the upper atmosphere they excited atoms causing them to give off light in many colours. Often the patterns of light take on the form of moving curtains and rays of light.

Diffuse red glow

Observers all over the Northern Hemisphere were stunned by the display.

A report from Chester, UK, by Tom Teague said that a bright diffuse red glow was visible, with many broad rays orientated roughly north-south. Some narrower, more concentrated rays with a greenish tinge were also seen.

Chartered engineer Ian Sheffield, of the Royal Observatory in Edinburgh, UK, who watched the display from his home in East Lothian, said: "It was the most amazing display I have seen in 10 years.

"They started at 1900 GMT and they looked like Jacob's Ladders coming down to the horizon. They were pale green with streaks of red that was quite unusual. It was ghostly."

Veils of pale green

The Duty Controller at the Jodrell Bank radiotelescope in Cheshire, UK, described the lights as very spectacular, with curtains of red and green light seen between 1130 and 0200 GMT.

A report from Dave Branchett in Florida, US, said: "These events are rare from this part of the world but even rarer was the sight of fingers or rays that shimmered and danced within the aurora."

Another observer said: "I've just spent the last two hours gazing up at a sky literally on fire with swaying red curtains and billowing veils of pale green and white streamers. Beams are everywhere. At one point, everything merged overhead, and staring up at it was like staring into some kind of pink wormhole - unbelievable."

It is expected that this storm will continue for the next 24-36 hours. The so-called geomagnetic storm may affect electrical power systems, spacecraft operations, and communications and navigation systems.