Key takeaways
- An M2.7 solar flare from sunspot region AR4392 launched a CME directly at Earth on 16 March
- NOAA issued a G2 Geomagnetic Storm Watch for 19–20 March, with an outside chance of G3
- Scotland and northern England had a genuine chance of seeing the northern lights on the night of 19 March
- The spring equinox effect makes March one of the best months of the year for aurora
- The best viewing window was forecast as 22:00–02:00 local time, facing north from dark skies
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For anyone living in Scotland, northern England, or Northern Ireland, the evening of 19 March was the one to clear. A solar eruption on 16 March sent a billion-tonne cloud of charged particles racing toward Earth at roughly two million miles per hour, and it was expected to arrive on 19 March, potentially lighting up the northern sky in green and purple.
What Happened on the Sun
At 12:15 UTC on Sunday 16 March, a moderate M2.7 solar flare erupted from active sunspot region AR4392 on the Sun's surface. The flare itself lasted only a few minutes, but the explosion was powerful enough to hurl a coronal mass ejection (CME), a vast bubble of magnetised plasma, directly toward Earth.
NOAA's Space Weather Prediction Center had by then revised its estimate upward, suggesting that as many as four CMEs may have been launched in quick succession: a phenomenon known as a "CME cannibal," where faster ejecta catch and merge with slower ones ahead, potentially amplifying the impact when the combined cloud struck Earth's magnetic field.
The official forecast was a G2 Moderate Geomagnetic Storm, with an outside chance of brief G3 Strong conditions. On the five-point NOAA storm scale, G2 is comfortably sufficient for aurora visibility across Scotland and northern England. G3 would have pushed the visible zone south into the Midlands and, in theory, parts of Wales.
The Equinox Effect
There was something quietly remarkable about the timing of this event. March 20, just one day after the CME was due to arrive, was the spring equinox, and it turns out that the weeks around both equinoxes are consistently the best times of year for aurora activity, even accounting for the solar cycle.
The reason has to do with geometry. Around the equinoxes, the angle between Earth's magnetic field and the solar wind is particularly favourable: a configuration called the "Russell-McPherron effect." When the orientation lines up just right, the incoming solar wind couples more efficiently to Earth's magnetosphere, funnelling more energy into the polar auroral zones. Statistically, geomagnetic storm rates double near the equinoxes compared to the solstices, even when solar activity is otherwise equivalent.
In plain terms: if you are going to get an aurora alert, you want it in March or September. That week delivered both.
Where in the UK the Aurora Was Forecast to Be Visible
Aurora visibility depends on two things: latitude and how strong the storm gets. Here was a straightforward guide for UK locations at the expected G2 level, with notes on a G3 upgrade:
Scotland (all regions): Very likely. Under G2, the whole of Scotland sat comfortably within the auroral zone. The Highlands, Orkney, and Shetland offered the best combination of latitude and (relative) darkness. Even city-dwellers in Edinburgh or Glasgow might have seen a green glow on the northern horizon if the storm peaked strongly.
Northern England and Northern Ireland: Good chance. Newcastle, Cumbria, Yorkshire, and Belfast all had realistic prospects under G2. The best chance came from getting away from town light pollution and facing north.
Midlands and Wales: Possible if G3 develops. Birmingham, Manchester, and Cardiff were marginal at G2 but would have come into range under G3 conditions. It was worth stepping outside and checking the northern horizon even in these areas.
Southern England: Unlikely under G2. London and the south coast were outside the expected visibility zone for a standard G2 storm. However, aurora cameras and long-exposure phone shots have surprised people further south before, so it was never entirely impossible, especially if the storm escalated overnight.
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When the Aurora Was Forecast
The CME was expected to arrive during the late afternoon or evening of 19 March, with geomagnetic activity ramping up through the evening hours UTC. The best viewing window for most of the UK was forecast as 22:00 to 02:00 local time on the night of 19–20 March, late enough for astronomical darkness, early enough that you were not entirely sleep-deprived.
A second CME might arrive later on 20 March, potentially extending activity into a second night. If cloud cover had spoiled Thursday, it might have been worth trying again on Friday.
For the most current outlook on the aurora, check our own live UK aurora forecast.
The key practical checklist before you go out:
- Check cloud cover for your location: this is as much a weather forecast as an astronomy one
- Drive or walk away from town, towards open northern horizon
- Give your eyes 20–30 minutes to dark-adapt before concluding the aurora isn't there
- Face roughly north to north-west
- Look for a green or white-ish glow sitting on the horizon: it often looks faint to the eye but vivid on camera
How to Photograph the Aurora
One of the best-kept secrets of aurora photography: your camera will almost always see more than your eyes. Even a modest DSLR or a modern smartphone in night mode can capture aurora displays that look faint or invisible to the naked eye. The northern lights are worth photographing even if you are not sure you can see them.
For a DSLR or mirrorless camera, the basic starting point is ISO 1600, aperture f/2, and a shutter speed of 10 seconds, then adjust from there. Shoot in RAW if you can, as it gives you far more latitude when pulling out the greens and purples in post. A wide-angle lens (14–35mm) maximises how much of the sky you capture, and a tripod is non-negotiable at these shutter speeds.
For smartphones, open your camera app's Pro or Night mode, set the exposure to around 8 seconds, and focus manually to infinity. Place your phone on something stable: a wall, a rucksack, or a small tripod. Samsung, iPhone, and most modern Android phones are capable of capturing a striking aurora image in these conditions.
How to Watch With Just Your Eyes
You do not need any equipment to enjoy the northern lights. But your eyes do need time. After arriving at your dark-sky location, resist the urge to check your phone: every time you look at a bright screen, you reset the dark adaptation clock back to zero. Give yourself a full 20–30 minutes of genuine darkness and you will be surprised at how much more you can perceive.
The aurora often appears first as a whitish haze or an arc sitting just above the northern horizon, people sometimes mistake it for distant cloud or light pollution. Watch for movement. Genuine aurora shifts, ripples, and occasionally dances rapidly. The green colour becomes much more obvious once the display intensifies.
One useful trick: look slightly to the side rather than directly at where you expect the aurora to be. The rods of the eye, responsible for low-light vision, are more densely packed away from the direct line of sight, so averted vision often reveals faint structure that stares straight at you without revealing itself.
How to Stay Updated
Aurora forecasts can change rapidly as a CME approaches and its exact parameters become clearer. The best sources to bookmark were the SpaceWeatherLive aurora alert page, the NOAA Space Weather Prediction Center, and the Met Office space weather forecast, which includes regular aurora probability updates for UK latitudes.
For mobile alerts, the SpaceWeatherLive app (iOS and Android) lets you set a Kp threshold notification: set it to Kp 5 and it will ping you the moment conditions hit the level needed for northern England. That way you do not need to stay up watching a website.
If this turns into a regular habit, our guide to seeing the northern lights in the UK has the full year-round strategy for catching the next display, whenever the alerts fire again.
If you captured something, it is always worth sharing to the @watchthestarsuk Instagram.
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Ian ClaytonAmateur astronomer and founder of WatchTheStars.co.uk, dedicated to helping others explore the wonders of our universe. Full profile →
