How to see the northern lights

ONE night in May last year, the sky over Zaragoza shimmered with ribbons of green and violet light — a spectacle that left onlookers spellbound.

It was an exceedingly rare sight for Spain: the northern lights, or aurora borealis, are typically reserved for regions close to the Arctic Circle — Norway, Finland, or Iceland.

Under exceptional circumstances, however, this phenomenon can move much farther south.

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A lucky few people in the north of Spain could witness this phenomenon for the second consecutive year.

The best time to see the northern lights is between October 22-29.

However, for city dwellers the show can be difficult to see. All three conspire to reduce the brightness of the show.

The best viewing conditions will be found in rural areas with dark, unpolluted skies — and the farther north, the better.

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Regions such as Asturias, Galicia, Cantabria, Navarra, and the Basque Country hold the most promise, though mountainous areas with clear skies and crisp air — like Catalunya or the Pyrenees — may also offer fine vantage points.

Skywatchers further inland will likely miss the main show, although some may be able to see a faint red glow ripple among the stars.

The best time to view the aurora is between midnight and 2am.

The displays are often short-lived, lasting only a few moments. But powerful solar storms may last for several hours.

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Typically, the lights ebb and flow — arcs of colour brighten suddenly before fading again, creating the enchanting illusion of a celestial dance.

When electrically charged solar particles slip through Earth’s magnetism and collide into gases in the air, the phenomenon occurs.

These collisions energise gas molecules which release the energy as waves.

Each color is a reflection of the chemistry in the atmosphere. For example, green and orange are produced by oxygen, while pink, purple and blue are caused by nitrogen.

Auroras occur more often near the poles because Earth’s shielding magnetic field is weaker.

But during powerful solar storms, that shield becomes disturbed, allowing the auroral oval — the ring around the poles where the lights are visible — to expand farther south.

This magnetic disturbance can be measured using a scale called the Kp Index. The higher the Kp number, the greater the disruption to Earth’s magnetic field — and the farther the aurora can reach.

The current solar storm striking Earth this week has a Kp value of six — precisely the kind of intense geomagnetic activity needed to bring the northern lights within view of Spain’s night skies.

Look up if, in the near future, you are under a clear, dark northern sky. You might even see the sky dance.

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