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A quite amazing and extensive aurora was visible from Northern Ireland during much of last evening and into the early morning. Astronomers at the Armagh Observatory were occupied for much of the evening in recording observations and taking photographs of the spectacular display.

The display was first seen when twilight ended as a prominent blue glow in the northeast. About 15 minutes later, at around 7:00 pm, a green aurora could be seen in the northeast.

A number of vertical bright green rays began appearing and disappearing quite rapidly well above the NW to NE horizon. A peak of activity occurred around 8:00 pm, when the aurora extended well beyond the overhead position into the southern sky. The aurora at one time covered a large section of the sky to an altitude of about 45 degrees above the southern horizon. The aurora continued until after 1:00 pm this morning.

The aurora, or Northern Lights, is caused when electrically charged particles, electrons and protons, emitted by the Sun during powerful magnetic eruptions, interact with the Earth's atmosphere. The particles stream down the lines of force of the Earth's magnetic field and transfer energy to the oxygen and nitrogen molecules in our atmosphere. This energy is then re-emitted from the molecules in the form of light. Green is the normal colour, but pink and red tints can sometimes be seen. The light is emitted from molecules at altitudes of between 80 and 100 kilometres.

At around midnight, the aurora took on an intense red hue towards the west southwest and a well-defined corona could be seen almost overhead from where green rays were diverging through the northern half of the sky. Also high towards the north, many fast-moving wavelike motions could be seen passing through the general aurora.

This auroral display seems to have been connected with the eruption of a so-called coronal mass ejection from the Sun on 28th October and sent the particles cascading towards Earth. There is currently much activity on the Sun and numerous sunspots can be seen, holding out the possibility of further aurorae in the coming hours. Great care should be taken when viewing the Sun and it should only be attempted with suitable equipment, otherwise permanent eye damage could be caused.

FOR FURTHER INFORMATION CONTACT: John McFarland at the Armagh Observatory, College Hill, Armagh, BT61 9DG. Tel.: 028-3752-2928; FAX: 028-3752-7174; jmfstar.arm.ac.uk; Website: http://star.arm.ac.uk/

Last Revised: 2003 November 3rd
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