Want to see the auroras? You're in luck: the Northern Lights is set to be visible across parts of the UK and US tonight.
For the first time since 2005, the National Oceanic and Atmospheric Administration's Space Weather Prediction Center (SWPC) has issued a G4 geomagnetic storm watch for this weekend, the second highest on its scale.
Sounds scary? While there are a few issues associated with the Sun sending a storm of high energy particles our way, for most of us there’s only one thing to worry about: will you catch a glimpse of the Northern Lights tonight?
Well, prepare to tick that item off your bucket list.
When can I see the northern lights?
Scientists expect the auroras to be visible tonight, Friday 10 May and into the early hours of tomorrow Saturday 11 May, across areas of the UK and US.
Enhanced geomagnetic activity is expected to persist throughout the weekend as Earth-directed Coronal Mass Ejections (CMEs) – giant bursts of gas and magnetism erupting from the Sun's surface, travelling millions of kilometres into space – reach Earth.
That said, tonight will likely be the peak of the activity, so it’s your best chance to spot the Northern Lights.
“To predict exactly where you can see the northern lights is difficult as conditions can change quickly,” says Prof Don Pollacco from the University of Warwick’s physics department.
“However, one thing is for sure, and that is that you are unlikely to see them from a brightly lit city environment – you need to go somewhere dark and look towards the northern horizon (look for the North Star). So, you would preferably be in the countryside away from street lights.”
The best time for viewing is typically during the darkest hours of the night, from around 11:00 – 12:00pm. But as Pollacco said, it’s difficult to predict exactly when they’ll crop up, so it could be a late night for any ardent aurora hunters.
According to astrophysicist Dr Paul Strøm, “The best way to see an aurora is to sign up to an alerts service which may provide the most current activity status.” For those in the UK, he recommends AuroraWatch UK. In the US, the SWPC has an account on X (formally Twitter) is a useful tool.
If you want to capture an image of the spectacle, Strøm advises “a long exposure image of a few seconds taken with the sensitivity of the camera turned up (higher ISO) on a tripod (or put on something else which keeps the camera still).”
Where can I see the auroras?
Otherwise known as the aurora borealis, the northern lights will be visible across much of the northern half of the US this weekend. As things stand, the states with the best chances of spotting them are in northern Montana, Minnesota, Wisconsin and most of North Dakota.
If we’re really lucky, the spectacle could stretch down as far as Alabama and northern California. This forecast is subject to change, so keep an eye on the SWPC’s aurora viewline prediction tool.
In the UK, the Met Office is forecasting auroras across the northern half of the country, “with a chance that aurora may become visible to all parts of the UK.”
Predicting exactly where auroras will be visible is always a tricky task, but with geomagnetic activity at such high levels, many people will certainly be in for a treat tonight.
Typically, auroras are visible near the magnetic poles of the Earth, which are roughly where the geographic poles are, so the further north you can get, the better. If you’re in or near the Arctic or Antarctic circles you can expect spectacular light shows too.
Read more:
- What causes the Northern Lights?
- What’s the furthest south the Northern Lights have been seen?
- Solar storms have dramatically increased this year. Should we be worried?
What causes auroras?
Thanks to its molten iron core that moves electric charge about, the Earth has a powerful magnetic field which interacts with particles ejected from the Sun – protecting life from harmful radiation and causing auroras in the process.
“Auroras are caused when huge magnetic bubbles of gas are ejected into space by the Sun,” Dr Darren Baskill, astronomy lecturer at the University of Sussex, tells BBC Science Focus.
“Occasionally, these bubbles collide with the Earth causing the Earth’s magnetic field to channel gas towards the north and south poles, causing the sky to glow with the shimmering lights of the aurora.”
Why are tonight's auroras enhanced?
Particles from the Sun are constantly battering the Earth, and auroras are commonplace near the poles. Tonight, however, marks a rare geomagnetic event, hence why we can expect auroras further south.
On Thursday, at least five Earth-directed CMEs were observed erupting from the Sun’s surface in quick succession. In particular, this activity is thought to be originating from a magnetic sunspot cluster 16 times the diameter of Earth on the Sun’s surface.
While the CMEs were spat out at different times, they also had different speeds and are expected to merge into one massive geomagnetic storm before they reach us at the end of today.
Part of the reason for this increase in activity is the Sun's 11-year cycle, where its magnetic field periodically gets stronger and weaker. Right now we’re heading towards the peak of this cycle, which means we can expect a lot more aurora over the next year or so as the Sun becomes increasingly active.
Why are auroras different colours?
The colours of the aurora borealis and australis (the Southern Lights) are determined by the specific atoms in Earth’s atmosphere engaging with solar particles.
Green is the most common auroral colour, produced when energetic electrons collide with oxygen atoms at high altitudes (100-300 km).
Collisions with oxygen atoms at even higher altitudes (around 300-400 km) cause a red glow. Reds are more common during periods of intense solar activity like tonight.
Blues and purples are less frequent still and require higher solar activity. They are produced by collisions with nitrogen molecules at lower altitudes (around 60 km or less).
Could the geomagnetic storm be dangerous?
To the general public geomagnetic storms pose little danger, although they can interfere with some high-frequency radio transmissions.
Experts will be watching aircraft and satellite communications carefully to make sure everything continues running smoothly.
Solar storms can also cause damage to power networks, such as in 2003 when a G5-level storm caused outages in Sweden and damaged transformers in South Africa. Tonight’s storm should be less powerful than that, though.
There’s also the possibility of more frequent and longer periods of interruptions to GPS systems.
About our experts
Don Pollacco is a professor in the astronomy and astrophysics group at the University of Warwick. His primary research interest is extrasolar planets, and he was responsible for the SuperWASP project in La Palma, which, along with its sister facility at SAAO, has become the most successful ground based planet detection experiment.
Dr Paul Strøm is an assistant professor in the astronomy and astrophysics group at the University of Warwick working on the PLATO space mission. He also works on various astrophysical topics mainly focused on far-UV observations aimed at understanding the formation environments of young planets.
Dr Darren Baskill is an outreach officer and lecturer in the Department of Physics and Astronomy at the University of Sussex. He previously lectured at the Royal Observatory Greenwich, where he also initiated the annual Astronomy Photographer of the Year competition.
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