Star-gazers enjoyed a rare spectacle last night as auroras - generated by one of the largest solar storms of the past 30 years - lit up the night sky.
Further effects of a violent eruption - or solar flare - that occurred on the sun on Tuesday morning are expected to be witnessed tonight as a huge mass of electrically-charged particles continues to bombard the earth.
Mr David Moore, chairman of Astronomy Ireland, said some of auroras seen last night were as "bright as morning twilight". Viewing was said to be best in northern counties, outside of urban areas where street lights dulled the effects.
Mr Moore said people should have another opportunity to witness the auroras tonight, emphasising that viewing the naturally-occurring phenomena was not dangerous.
However, he said anyone seeking to look at the sunspots from which the solar flares erupted should wear guaranteed protective eye-wear.
Normally astronomers have to travel close to the poles - to which the Earth's magnetic field channels solar particles - to witness an aurora, which occurs naturally as the northern lights or aurora borealis.
Meanwhile, emergency services worldwide were bracing themselves for possible blackouts resulting from the solar activity.
Dr John Kohl, a solar astrophysicist at the Harvard-Smithsonian Centre for Astrophysics in Cambridge, Massachusetts, said the flare was the third-largest recorded since 1976.
It is the largest, however, to be pointed directly at Earth, raising the possibility of widespread power surges or blackouts, and disrupted television and mobile phone signals. At least one satellite was knocked out of action by the storm yesterday. Japan's space agency said its Kodama communications satellite had been temporarily shut down after malfunctioning due to the flare.The solar observation satellite, SoHo, has also been shut down as a precautionary measure.Its geographical location some distance from Earth's poles means Ireland is unlikely to suffer disruption.
Shorter power lines to those used in countries like Canada are also said to insulate Ireland from the effects of power surges. A spokesman for the ESB noted it had never previously been affected by solar flares and "we do not expect it to have any effect on this occasion on the Irish power supply".
In the US, fears have been raised that power surges could hamper ongoing fire-fighting in southern California.
Wildfire has already knocked out many microwave communication antennas on the ground, making satellite communications important to emergency efforts.
In 1989, Quebec suffered a blackout when a similar geomagnetic storm knocked out the whole of its power grid.
While the impact of Tuesday's eruption - 13 times the size of the Earth and travelling at more than a million m.p.h. - would be counteracted by Earth's magnetic shield, Dr Kohl said "major effects" were still expected.
Mr Larry Combs, forecaster for the US Space Weather Centre, said the storm - rated a G5, the highest intensity on scientists' scale of space weather - was "extremely rare . . . We know that our power grids are definitely feeling the effects of this."
Mr Moore noted the only networks in Ireland expected to be affected by the electrical activity were high-frequency radio communications.
Astronomy Ireland is organising viewings of the activity throughout the country and aurora-watchers are asked to post details of their observations on its website www.astronomy.ie
