Royal Astronomical Society press release
RAS PR 15/30 (NAM 8)
3 July 2015

On Saint Patrick’s Day (17 March) the northern lights danced a lively green jig across the skies of Ireland and Britain. The source of these magnetic storms was not just one but two huge eruptions of electrically charged material from the Sun, which travelled through space at millions of kilometres an hour, colliding with the Earth’s magnetic field.

The resulting geomagnetic storms - the strongest for a decade - led to dramatic displays of the northern lights and induced significant additional currents in the power grids of Britain and Ireland. Despite that, neither grid suffered any damage, boosting the prospects for resilience when worse ‘space weather’ events take place.

Two research groups, led by Peter Gallagher of Trinity College Dublin and Gemma Kelly of the British Geological Survey (BGS), will this week (7 and 8 July) give presentations on the effects of the storm this week at the National Astronomy Meeting at Venue Cymru in Llandudno, Wales.

As far back as 1852, Dublin-born Sir Edward Sabine showed that magnetic storms waxed and waned with the number of spots on the Sun. Not long after this, in 1859, Richard Carrington observed a huge solar flare that was followed within a day by brilliant displays of the northern lights in regions as far south as Italy and Cuba.

In addition to brilliant auroral displays, the electric telegraph – the Victorian internet - was found to be disrupted during periods with large geomagnetic storms. The Daily News of September 1859 reported, “the electric telegraph was disrupted … owing to some mysterious atmospheric influence.”

Nowadays, society has become vastly more dependent on technological systems for communications and electricity. These too can be disturbed by magnetic storms - navigation systems can have positioning errors, radio transmission can be blacked out, and power grids can become unstable. The most infamous impact occurred in 1989 in Canada, when a magnetic storm interrupted electrical power for more than six million people for nine hours at a cost of over C$13 billion (£6.6 billion, 9.3 billion Euros).

For this reason scientists at Trinity College Dublin and at the British Geological Survey were on high alert this Saint Patrick’s Day. “A warning message from our magnetometer network developed by Trinity and the Dublin Institute for Advanced Studies notified me of the onset of a large geomagnetic storm as I watched the Saint Patrick’s Day parade with my family”, according to Professor Peter Gallagher, head of solar physics and space weather at Trinity. “That evening, the sky danced red, pink and notably green across Ireland and the UK.”

The scientists’ attention immediately turned to potential effects on communications and electrical power systems. “My research student Sean Blake quickly ran the British Geological Survey’s magnetic storm model to see if there were any threats to the Irish power grid”, said Gallagher. “Despite the storm’s size, no significant effects were predicted or indeed reported.”

Dr Kelly added: “This storm and a more recent one in June were the biggest we have seen in over 10 years. They produced the biggest electrical fields on the ground – and hence currents – we have seen since our system started operation in 2012. Fortunately, the British power grid held up well too, so it gives us more confidence that at least some of our systems are pretty resilient to inclement space weather.”

The Saint Patrick’s Day storm has enabled the Trinity team to demonstrate that their alert system works in Ireland and helped BGS scientists gather data on how the storms affected Britain. Blake concludes, “We can now monitor and model magnetic storms in near-real time, which not only allows us to understand the physics of such phenomena, but also to provide a valuable service for power operators.”

Images and captions

The aurora borealis lighting up the sky green for Saint Patrick’s Day (17 March) 2015. This image was taken from Co. Mayo and shows the display above a sea stack known as Dún Briste. According to one legend, a pagan chieftain named Crom Dubh lived there. He refused to listen to Saint Patrick who tried to convert him to Christianity. St. Patrick hit the ground with his crozier and the stack was separated from the mainland, leaving Crom Dubh to die there. (c) Brian Wilson.


Map of the modelled changes in electric field caused by the St Patrick’s Day storm, where blue is low and red is high. Large geomagnetic storms can cause unwanted currents to flow through electrical power grids. On this occasion though, no damaging effects were seen in the Irish or British power grid. Credit: Gemma Kelly / BGS


A graph showing how compass direction changed during the 17 March geomagnetic storm, measured at three observing stations across the UK. The storm was powerful enough to shift the apparent direction of magnetic north by several degrees. Credit: BGS

Media contacts

Dr Robert Massey
Royal Astronomical Society
Mob: +44 (0)794 124 8035
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Ms Anita Heward
Royal Astronomical Society
Mob: +44 (0)7756 034 243
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Dr Sam Lindsay
Royal Astronomical Society
Mob: +44 (0) 7957 566 861
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Science contacts

Prof Peter Gallagher
School of Physics
Trinity College Dublin
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Mr Sean Blake
Trinity College Dublin
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Dr Gemma Kelly
British Geological Survey
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Further information

The Irish magnetometer network is being developed by Trinity College Dublin and the Dublin Institute for Advanced Studies. Sean Blake is supported by a studentship from the Irish Research Councils’ Enterprise Partnership Programme which funds cooperation between Trinity College Dublin and Eirgrid Plc. EirGrid is a responsible for the provision of electrical transmission and market services in Ireland. Models of geomagnetic storm effect are provided by the British Geological Survey.

Notes for editors

The Royal Astronomical Society National Astronomy Meeting (NAM 2015) will take place at Venue Cymru in Llandudno, Wales, from 5-9 July. NAM 2015 will be held in conjunction with the annual meetings of the UK Solar Physics (UKSP) and Magnetosphere Ionosphere Solar-Terrestrial physics (MIST) groups. The conference is principally sponsored by the Royal Astronomical Society (RAS) and the Science and Technology Facilities Council (STFC). Follow the conference on Twitter


The Royal Astronomical Society (RAS), founded in 1820, encourages and promotes the study of astronomy, solar-system science, geophysics and closely related branches of science. The RAS organises scientific meetings, publishes international research and review journals, recognizes outstanding achievements by the award of medals and prizes, maintains an extensive library, supports education through grants and outreach activities and represents UK astronomy nationally and internationally. Its more than 3800 members (Fellows), a third based overseas, include scientific researchers in universities, observatories and laboratories as well as historians of astronomy and others. Follow the RAS on Twitter


The Science and Technology Facilities Council (STFC) is keeping the UK at the forefront of international science and tackling some of the most significant challenges facing society such as meeting our future energy needs, monitoring and understanding climate change, and global security. The Council has a broad science portfolio and works with the academic and industrial communities to share its expertise in materials science, space and ground-based astronomy technologies, laser science, microelectronics, wafer scale manufacturing, particle and nuclear physics, alternative energy production, radio communications and radar. It enables UK researchers to access leading international science facilities for example in the area of astronomy, the European Southern Observatory. Follow STFC on Twitter


The British Geological Survey (BGS), a component body of the Natural Environment Research Council (NERC), is the nation's principal supplier of objective, impartial and up-to-date geological expertise and information for decision making for governmental, commercial and individual users. The BGS maintains and develops the nation's understanding of its geology to improve policy making, enhance national wealth and reduce risk. It also collaborates with the national and international scientific community in carrying out research in strategic areas, including energy and natural resources, our vulnerability to environmental change and hazards, and our general knowledge of the Earth system.


The Natural Environment Research Council (NERC) is the UK's main agency for funding and managing world-class research, training and knowledge exchange in the environmental sciences. It coordinates some of the world's most exciting research projects, tackling major issues such as climate change, food security, environmental influences on human health, the genetic make-up of life on earth, and much more. NERC receives around £300 million a year from the government's science budget, which it uses to fund research and training in universities and its own research centres.