Yes, sometimes. From Bern, it’s worth stepping outside when the aurora oval has pushed south over Europe and you can see a dark, clear stretch of northern sky. You can make that decision from home before waking anyone up.
Key takeaways
- Start with your own sky. Check whether you can see stars low in the north. A clear patch directly overhead can be misleading.
- Use Kp to pick the evening. A high value tells you a geomagnetic storm is under way or forecast. Its timing matters as much as the number.
- Use the oval to pick the moment. Find Europe on the Northern Hemisphere map and read the forecast time on the image.
- Follow the Bz trace. A sustained southward magnetic field in the solar wind favours auroral activity. A brief dip is a poor reason to set off.
- Look before taking a picture. A phone can bring out colour in a glow that looked grey to you. Keep both versions of the observation.
The question at home
The family chat has a picture of a pink sky. Someone asks, “Can we see it too?” Before you hunt for shoes, ask where and when it was taken. A photo taken near Bern minutes ago is a reason to go to the window. Check the location before you pass along a holiday snap from Norway.
Open the curtains before the forecast. Find north on a map, then pick a roof, tree or ridge you can recognise in that direction. Can you see stars above it? If you can see the stars overhead but the ridge disappears into a pale bank of cloud, you already know something the aurora map can’t tell you. If the window reflects the kitchen, switch the light off or step outside.
For the two live views you actually need, put the Northern Hemisphere aurora map beside the cloud forecast for Bern. Set the weather map to your viewing hour. Check the valid time on the aurora map. Add one hour to UTC in Swiss winter time, two in summer. Save the map if you plan to compare it with what you see. NOAA aurora map · MeteoSwiss cloud cover · Bern time zone
What physics allows
Kp tells you how disturbed Earth’s magnetic field has been. Instruments on the ground measure magnetic variations, which are combined into a planetary index on a scale from 0 to 9 for each three-hour interval. A forecast Kp describes an interval still to come. The latest estimated Kp uses measurements already arriving. If a screenshot says “Kp 7”, check which one it shows before making plans for the evening. GFZ’s Kp index · NOAA’s estimated Kp · three-day forecast
Aurora forms when energetic particles excite atoms and molecules high in the atmosphere. The glow forms a lopsided ring around the magnetic pole, the auroral oval. During a storm it can expand towards Switzerland. The altitude helps us here. Think of a distant tower whose top is still visible beyond a hill. Likewise, the red top of a distant aurora can clear your horizon while lower green light stays hidden. From Bern, start by looking low towards the north. NOAA’s viewing guide · Research on red auroral arcs
Bz gives you an upstream clue. The solar wind carries a magnetic field. On NOAA’s solar-wind plot, the line labelled Bz shows its north–south component in the GSM coordinate system. Below zero means southward. If it stays southward for a while, energy can pass more readily into Earth’s magnetic environment. Follow the shape of the line across the recent plot. Even a long southward stretch leaves open where the brightest part of the oval will develop. NOAA solar-wind plot · How geomagnetic storms develop
The OVATION map uses those same upstream measurements to estimate where the aurora will be brightest, usually about 30–90 minutes ahead. If the solar-wind data drop out, NOAA can use current Kp instead. That fallback has no forecast lead time. Find Scandinavia as a landmark and look for the bright band on the European side. The redder shading means a stronger modelled display. It doesn’t predict the colour you’ll see. Bright, high aurora can also be visible from outside the shaded band. Use NOAA’s hemispheric map for Bern. Its separate “Tonight and Tomorrow Night” viewline product covers North America. NOAA’s model and map key · Viewline coverage
What tests show
Two nights in May 2024 show the difference between a storm report and a sighting. On the night of 10–11 May, the University of Bern reports that people in Switzerland could see red, pink and green aurora with the naked eye, even from cities. Near Bern, the all-sky camera at Uecht recorded aurora to the north at about 22:35 local time on 10 May. In Dübendorf, the photographs reproduced by the university used 2.5-second exposures. The camera gathered light throughout each exposure, making the colours appear more vivid than they did to an observer. The storm reached G5, the highest category on NOAA’s geomagnetic storm scale. University of Bern’s observation report and photographs · Uecht camera record · NOAA’s G5 bulletin
The following night, the university team went to its observatory in Zimmerwald, near Bern. There was still a faint glow towards the north, but this time it appeared only in the pictures. The researchers point to the less favourable orientation of the interplanetary magnetic field that night. Even observers who knew exactly where to look needed a camera on the second night. Zimmerwald field account
How much confidence should you put in the map? Researchers tested an earlier version of OVATION against satellite ultraviolet imagery from 1997 and 1998. Across the conditions they tested, its yes-or-no forecasts agreed with the satellite-based assessment 77% of the time. The test concerned auroral emission as seen from space. It didn’t count people standing under clear or cloudy skies in Bern, so that percentage can’t tell you your odds tonight. Machol et al., model validation
Status of the key claims. That an oval expanding towards central Europe, a sustained southward Bz and stars visible low in your northern sky together make a short look worthwhile is supported by the Swiss observations of May 2024 (University of Bern). That a camera can show aurora the eye misses is supported by the same reports. That stepping behind a wall that screens a nearby lamp makes a faint arc easier to distinguish is untested; you can compare the two views on the same evening (NASA’s observing guide).
What you can do anyway
Before supper, pick your spot. Start with a familiar path with open ground to the north. You can spare yourself a long drive to an unfamiliar mountain. If the city lights fill the northern view, a darker patch of ground behind you won’t solve the problem. Choose somewhere you can reach easily and where a child can look over the foreground as comfortably as an adult. NASA’s guide to finding auroras
After dusk, make the go-or-stay decision. Sunset is the beginning of evening twilight. Give the northern sky time to darken, and check what the clouds are doing between you and the horizon. A bright Moon or a veil of haze can wash out the faintest glow. For tonight’s timing use the twilight columns for Bern. For tonight’s clouds use the map, then look out of the window again. Bern twilight times · MeteoSwiss cloud cover
| What you find | What to do from Bern |
|---|---|
| High Kp forecast later, European oval still far north | Stay close to home. Reopen the oval during the forecast interval. |
| Oval expanding south over Europe, Bz mostly southward, clear northern sky | Step outside now. Start at the northern horizon and slowly scan higher and to either side. |
| Promising oval, solid cloud to the north | Check for a later break. A fresh photo from somewhere else tells you little about the cloud in front of you. |
Once outside, let your eyes adjust. Keep bright screens out of view and give everyone a turn before showing them a picture. Ask what shape they see and where it sits relative to your landmark. A faint grey arc is a perfectly good description. Then steady the phone on a wall or tripod, take a night-mode picture in the same direction and keep the original. If there’s a pink patch, try another frame with the streetlamp screened. A single coloured patch is hard to identify. A sequence with a fixed skyline gives you more to compare. NASA’s photography guide
Tomorrow morning, compare the forecast with what happened. Note the local time, direction, cloud and what each person could see before looking at the photograph. Then compare the saved forecast with the observed Kp for that interval and your notes from the same time. “Stars clear above the ridge, nothing seen by eye, faint pink on camera” is a useful entry. So is “cloud covered the ridge”.
Quick questions
Is Kp 6 enough for Bern? Sometimes. At Kp 6, NOAA’s rough guide puts the oval’s southern edge near 54° magnetic latitude. That’s a typical location of the light itself. How far south someone can see it depends on its height, brightness and the view. NOAA’s viewing guide
Do I need to see green curtains? No. A low reddish band or a pale arc is worth checking from Switzerland. Compare it with your skyline, a second frame and observations from the same region and time. University of Bern
Is it worth waking the children? Try the view yourself first. Once you can point to an arc above a familiar tree or roof, you can give them something to look for the moment they step outside.
Related on SolarHealth
Sources and live tools
- GFZ, About the Kp index.
- NOAA SWPC: estimated planetary Kp, three-day forecast, real-time solar wind, geomagnetic storms.
- NOAA SWPC: Northern Hemisphere OVATION forecast, aurora viewing guide, North American viewline, G5 conditions observed, 10 May 2024.
- University of Bern, Space Weather events May 2024. Solarpatrol, Uecht all-sky observations.
- Machol et al., Evaluation of OVATION Prime as a forecast model for visible aurorae. Gillies et al., Identifying the 630 nm auroral arc emission height.
- MeteoSwiss, cloud cover. Timeanddate, twilight in Bern and Bern time zone. NASA, Guide to Finding and Photographing Auroras.
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