Solar storm 'may trigger' northern lights
A strong geomagnetic storm which could affect power grids, airplane routes and space-based satellite navigation systems across the world, could also trigger the northern lights over Ireland tonight and tomorrow.
The storm, a cloud of charged particles flung from the Sun at about 4.5 million miles per hour (7.2 million km per hour), was spawned by a pair of solar flares and is currently pounding the Earth, according to scientists.
This is probably the strongest such event in nearly six years, and is likely to be more intense than a similar storm in late January, said Joseph Kunches, a space weather specialist at the US National Oceanic and Atmospheric Administration (NOAA).
US weather experts said the storm was expected to hit Earth between 06.00am and 10.00am (Irish time) today.
This flare was categorised as an X5.4, making it the second largest flare - after an X6.9 on August 9, 2011 - since the sun's activity segued into a period of relatively low activity called solar minimum in early 2007.
Astronomy Ireland said there is a significant chance that the Aurora Borealis (northern lights) will be visible from Ireland as a result of the solar storm.
It will most likely be visible just over the northern horizon, but a strong display can result in the aurora being visible further south.
The organisation says locations just outside a town or cities, or dark parkland areas, are best suited for viewing if the sky is dark and a clear northern horizon is in view.
The current increase in the number of X-class flares is part of the sun's normal 11-year solar cycle, during which activity on the sun ramps up to solar maximum, which is expected to peak in late 2013.
This solar disturbance occurs in three stages with the first two already affecting Earth.
Two solar flares moving at nearly the speed of light reached Earth late on Tuesday and solar radiation hit Earth's magnetic field yesterday.
The plasma cloud sent by the coronal mass ejection "which is basically a big chunk of the Sun's atmosphere", is expected to arrive at Earth early today, Mr Kunches said.
This phase can disrupt power grids, satellites, oil pipelines and high-accuracy GPS systems used by oil drillers, surveyors and some agricultural operations, scientists said.
GPS systems used for less-refined functions, such as the turn-by-turn navigation found in many cars, should not be affected, according to NOAA's Doug Biesiecker.
Mr Kunches said the geomagnetic component of the storm may arrive a bit ahead of schedule because it follows a previous storm that left the Sun on Sunday and is currently buffeting the Earth's magnetosphere.
"When you've already had one coronal mass ejection storm, sometimes the next coronal mass ejection storm is faster to get here," he said.
These storms could produce some vivid auroras, according to experts. In the Northern Hemisphere, the aurora borealis could be visible at mid-latitudes, which in the United States could include New York, Illinois and Iowa.
Such stormy space weather is unusual in recent history, according to Harlan Spence, an astrophysicist at the University of New Hampshire who is principal investigator on the Cosmic Ray Telescope for the Effects of Radiation (Crater) aboard Nasa's Lunar Reconnaissance Orbiter.
"These relatively large (solar) events, which we've had maybe a couple of handfuls total in the course of a decade, we've now had two or three of them, more or less right on top of each other," Mr Spence said by telephone.
The Sun is on the ascendant phase of its 11-year cycle of solar activity, with the peak expected next year, scientists said.
"It's a clear harbinger that the Sun is waking up," Mr Spence added.
"We're trying to put this in context not only ... of what has the Sun done in the past, but what is the biggest thing the Sun is capable of and what should we be planning for in terms of extreme sorts of events in the future."