Sky watchers across the United Kingdom could witness a spectacular display of the northern lights tonight as a fast-moving coronal mass ejection from the Sun arrives at Earth, potentially triggering geomagnetic storm conditions ranging from moderate to severe.
The Met Office has confirmed that the coronal mass ejection (CME), which departed the Sun late on Saturday 30 August, arrived at Earth late on 1 September and is expected to create conditions that could allow the aurora borealis to be visible much further south than usual, potentially across much of the UK without the need for photographic equipment.
Geomagnetic activity is forecast to reach G2 to G3 levels (moderate to strong) on Monday night, with a chance of reaching G4 (severe) conditions, according to both the Met Office Space Weather Operations Centre and international forecasting partners. These storm levels could extend into Tuesday 3 September, depending on the extent of the magnetic cloud associated with the CME.
As we monitor the arrival of this coronal mass ejection, there is a real possibility of aurora sightings further south than usual on Monday night,” said Krista Hammond, Met Office Space Weather Manager. “While the best views are likely further north, anyone with clear, dark skies should keep an eye out. Forecasts can change rapidly, so we encourage the public to stay updated with the latest information.”
A coronal mass ejection is a massive release of plasma and magnetic field from the Sun’s corona, the outermost part of the Sun’s atmosphere. These ejections can travel at speeds of up to several million kilometres per hour and, when directed towards Earth, interact with our planet’s magnetic field to trigger geomagnetic storms and produce spectacular aurora displays.
The intensity and geographical reach of aurora displays depend on several factors, including the strength and magnetic orientation of the CME, as well as local weather conditions and light pollution levels on the ground. The current event is particularly noteworthy as it could produce aurora visible to the naked eye across much of the UK, a relatively rare occurrence for locations this far south.
However, several factors may affect visibility tonight. Weather forecasts for 1 to 3 September indicate significant cloud cover throughout the evening across many regions. The Midlands appears most likely to have the least cloud cover on 1 September, potentially offering the best viewing conditions in central England.
Viewing conditions are expected to worsen on 2 and 3 September, with northern Scotland and northern England likely to have the clearest skies, though forecasters note these will still not be ideal conditions for aurora watching.
The presence of a waxing gibbous moon will also pose challenges for observers, particularly in areas already affected by light pollution. The moon’s brightness could impede clear views of the aurora, especially in marginal locations further south or in urban areas where light pollution plays a significant role in determining visibility.
The Met Office Space Weather Operations Centre reported that solar winds, as measured by the Advanced Composition Explorer (ACE) spacecraft, increased dramatically from background levels of 380-480 km/s to a strong 670 km/s following the CME arrival. The interplanetary magnetic field strength also became notably strong after the CME impact.
During the initial arrival period on 1 September between 21:00 and 23:59 UTC, geomagnetic activity reached Kp6/G2 moderate storm levels. The count rate of high-energy protons increased ahead of the CME arrival but remained below the S1/Minor Radiation Storm threshold, though forecasters note there remains a slight chance that any significant solar flares could push these levels higher.
Looking ahead, the potential for aurora sightings may continue on Tuesday night into Wednesday, though these displays are more likely to be confined to northern parts of the UK. By Wednesday night, no significant solar activity is currently expected, and the likelihood of further aurora sightings diminishes accordingly.
The geomagnetic storm scale used by the Met Office and the US National Oceanic and Atmospheric Administration rates storms from G1 (minor) to G5 (extreme). G2 storms can affect power systems at high latitudes and spacecraft operations, whilst G3 storms can require voltage corrections in power systems and create intermittent satellite navigation problems. G4 severe storms, if reached, could cause more widespread voltage control problems and affect satellite operations.
For those hoping to photograph the aurora, the Royal Photographic Society recommends using a tripod for stability, setting a high ISO (1600-3200), using a wide aperture (f/2.8 or lower if possible), and experimenting with exposure times between 5 and 25 seconds. Even smartphone cameras can capture aurora displays with the right settings and conditions.
This solar event follows a period of heightened solar activity as the Sun approaches the peak of its 11-year cycle. The current solar cycle, known as Solar Cycle 25, has been more active than initially predicted, leading to more frequent opportunities for aurora sightings at lower latitudes.
The Met Office emphasises that solar weather forecasts can change rapidly, especially following the observation of a sudden CME. Whilst the waxing gibbous moon and potential cloud cover may hinder visibility in some areas, those with clear and dark skies could be rewarded with a rare and memorable display of nature’s most spectacular light show.
Sky watchers are advised to find locations away from city lights, allow their eyes to adjust to darkness for at least 20 minutes, and look towards the northern horizon. The aurora can appear as anything from a faint green glow on the horizon to dramatic, dancing curtains of green, red, and purple light across the sky.
The Met Office will continue to monitor the situation and provide updates as conditions develop. Those interested in viewing the aurora are encouraged to check the latest space weather forecasts and local weather conditions before venturing out.
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Image Credit:
Northern lights over Mývatn (Iceland) — photograph by Giles Laurent, taken on 27 March 2022. Licensed under Creative Commons Attribution–ShareAlike 4.0 International (CC BY-SA 4.0).
Attribution should be formatted as: © Giles Laurent, gileslaurent.com, License CC BY‑SA 4.0
