Those in the UK should look northwards for the aurora tonight as the aftermath of the biggest solar flare for more than a decade continues to pummel Earth

Watch out for the northern lights tonight – UK could be in for a big display

The particle ‘debris’ created by a monstrously large solar flare reached Earth at around 00:00 BST last night. It sparked displays of the northern lights that were seen as far south as Edinburgh in Scotland and Arkansas in the US.

At 00:12 BST, Lancaster University’s Aurorawatch issued an amber alert, meaning that aurora is likely across Scotland, northern England and Northern Ireland. A dozen minutes later, they upgraded to red alert, saying “It is likely that aurora will be visible by eye and camera from anywhere in the UK.”

Experts say that the storm is still raging around our planet today and could continue or even intensify into this evening. This makes it possible – though not guaranteed –that another spectacular display of aurora could be seen tonight.

To see the aurora requires clear, dark skies, usually well away from streetlamps and other light pollution. Look north, because the phenomenon creeps down from the polar regions.

Jean-Loup Rebours-Smith tweeted this image of the aurora over Edinburgh last night.

Faint aurora can appear as misty patches of grey light that can change their shape and configuration. Stronger displays that trigger the colour receptors in our eyes can be green or red in colour. They can appear as filaments or shifting ‘curtains’ across the sky.

The aurora is caused when charged particles (smashed up atoms) from the Sun collide with atoms in our atmosphere, giving off light. As of this morning, spaceweather.com was reporting that they were still blowing a gale past Earth, with solar wind speeds of around 700 kilometres per second. (The windspeeds in Hurricane Irma peak at around 240 kilometres per hour.)



At the time of writing, aurora-service.eu shows that most of Scandinavia is engulfed (although the lights are not visible because it is day time). The northern top of Scotland also falls just under the auroral oval.



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The particles that spark the aurora originate in solar flares. The energy released in these explosions can be more than a billion times the energy of an atomic weapon, and blow away a chunk of the Sun’s outer atmosphere. Known as a coronal mass ejection, this ‘magnetic cannonball’ contains the charged particles that spark the aurora if they happen to hit the Earth.

This particular solar storm began on Wednesday when the largest solar flare for more than a decade exploded on the Sun.

In general, the Sun is winding down in its activity in preparation for a regular lull known as solar minimum. Yet, large flares are known to happen in this declining stage.

This was the case in 1859 when the Carrington event, the largest solar storm on records, struck our planet. It sparked aurora in two thirds of the skies across the globe and its electrical interference temporarily rendered telegraph stations and compasses useless.

Today, spacecraft, telecommunications and power generators can be at risk from solar storms. Indeed, Wednesday’s flare instantly caused a temporary short-wave radio blackout over Europe, Africa and the Atlantic Ocean. This is why astronomers are investing a lot of effort is studying the Sun to warn of incoming blasts.

For most of us, however, the aurora is just a spectacular natural light show. You can check the auroral conditions and sign up for email alerts at Aurorawatch.

Stuart Clark is the author of The Sun Kings (Princeton).