Highlands & Islands

Rise in alerts to sightings of the aurora borealis

Wednesday's aurora from Ullapool Image copyright Noel Hawkins
Image caption Wednesday's aurora from Ullapool in Wester Ross

Lancaster University's AuroraWatch UK has issued more amber alerts for sightings of the aurora so far this year than in 2013 and 2014 combined.

Amber is the organisation's second highest alert to draw the public's attention to opportunities of seeing the Northern Lights.

This year 14 have been sent out and just two last year and eight in 2013.

Displays were visible from Scotland, Northern Ireland and north England and Wales on Wednesday night.

In some places, such as Inverness, the aurora was powerful enough to be visible through thin cloud.

Image copyright AP
Image caption The Northern Lights on Wednesday were visible from north England, including the Lake District

AuroraWatch UK has four levels of alert with green at the lowest end to yellow, amber and red.

Amber means the Northern Lights are likely to be visible from Scotland, north England and Northern Ireland. Twelve amber alerts were issued in both 2011 and 2012.

Red means that the aurora is likely to be seen from everywhere in the UK.

Clear skies are key to viewing the spectacular displays.

'Aurora hunting'

The aurora borealis is caused by the interaction of solar wind - a stream of charged particles escaping the Sun - and Earth's magnetic field and atmosphere.

A spokesman for AuroraWatch UK said: "The Sun's activity varies over time going from solar minimum, when the Sun is relatively quiet, to solar maximum when the Sun is particularly active.

"The time between two solar maximums is approximately 11 years and is known as the solar cycle.

"Solar maximum last occurred in 2014 and we are now in the declining phase of this current solar cycle."

Image copyright Noel Hawkins
Image caption A 'fortuitous combination' of events has made the aurora borealis more likely

During the declining phase, increased numbers of high speed solar wind streams flow from the Sun.

The spokesman said: "There is also a seasonal effect, with the equinoxes resulting in increased auroral activity.

"Whilst it is currently unknown why this is the case, it is likely due to the orientation of the Earth's magnetic field with respect to the incoming solar wind."

He added: "This fortuitous combination of seasonal variation, the declining phase of the solar cycle, and the approach of winter with its darker evenings makes this a particularly good time for aurora hunting."

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