Light show set to continue

The view from Colorado (Image courtesy of Mark Cunningham)

By BBC News Online science editor Dr David Whitehouse

The largest sunspot group in over a decade may be shrinking, but it still managed to let off another gigantic flare on Sunday.

The Southern Lights viewed from Dunedin, New Zealand (Image courtesy of Chris Petrich)

The explosion has sent another cloud of hot, electrically charged gas towards the Earth. When it reaches us on Tuesday, scientists predict, there will be another fine display of aurorae like those visible from the US on Saturday.

The sunspot group, designated Noaa 9393, is now being carried to the Sun's edge by solar rotation, but it is still capable of producing further flares. This is because it still has a lot of energy stored in its magnetic sheath that could be released at any time.

"Noaa 9393 has been a great sunspot group," said Robin Scagell, of the UK's Society for Popular Astronomy, "and it may not have finished yet."

Idaho was one of the best places (Image courtesy of Forrest Ray)

As skywatchers wait for Tuesday's possible display of aurorae, more reports are coming in of Saturday's magnificent spectacle that was caused by an explosion on Noaa 9393 on Thursday.

The whole sky lit up in South Dakota (Image courtesy of Brian Klimowski)

The American space agency's (Nasa) Polar Orbiting Environmental Satellite (Poes) caught the ring of light positioned over the Earth's northern magnetic pole, produced by charged particles from the Sun being funneled down on to the planet by magnetic forces.

Observers in the western US had the best view, reporting fine displays of deep orange and red streamers with an overall red glow that stretched from the northern horizon to beyond the zenith.

Aurorae were also detected in the Southern Hemisphere. Some observers saw them as a diffuse red glow visible from more northerly latitudes than is usual.

UK observers got a poor view. Jim Henderson in Aberdeenshire said he saw a fairly widespread diffuse red glow, but it was very vague and nowhere near as good as the display of last year.

The Poes satellite tracked the Northern Lights

Another view from Idaho