This winter and next, a clear northern night sky is something to look forward to.
"There is a good chance that some nights we will see real auroral fireworks," says Tiera Laitinen, Team Leader for Space Weather Research at the Finnish Meteorological Institute.
The intensity of the solar wind that creates auroras varies randomly, but the Sun also has a cycle of about 11 years when it is at its most active. And, this peak is approaching, even though the exact timing is not known.
"That's when the solar wind is at its strongest and the gusts are fierce," he says. "The next peak in activity has been forecast for 2025, but it could come as early as this year. The variability of the solar activity cycle is not yet well modelled or explained."
Sun's magnetic field
The variation in solar activity is caused by the Sun's magnetic field. Laitinen explains that the solar magnetic field is generated by a complex process called the solar dynamo.
When the Sun's activity is at its minimum, the magnetic field is weak. Then the magnetic field begins to increase and become stronger at the same time as it begins to fluctuate.
Eventually, the magnetic field sort of breaks down and starts to reverse.
"So every 11 years or so, the Sun's magnetic field reverses direction and starts to build up again," Laitinen notes.
Sometimes the peaks of solar activity are stronger, sometimes weaker. The faster the peak in activity approaches, the stronger it is.
According to Laitinen, the upcoming peak will be stronger than the last one.
"If we take a longer term view, we could say that the intensity will perhaps be more or less in the middle range," he says.
Links to Earth-bound effects
As the Sun becomes more active, scientists are also monitoring disturbances in the Earth's magnetic field. These are linked to the aurora.
Researchers have found that there are also auroral storms in summer similar to those in winter. They simply aren't visible in the bright sky.
"The Finnish Meteorological Institute (FMI) has a dozen observation stations in Finland. They are wooden boxes with magnetometers. The equipment constantly measures the Earth's magnetic field. It detects even small changes, and a computer sends the results to us in real time," Laitinen says.
This data is analysed in a number of ways. For example, when a magnetic change is detected at several locations, it can be used to calculate the electrical currents in the upper atmosphere that caused the change.
The FMI publishes near real-time information on aurora activity and the previous 24 hours' geomagnetic disturbances on its "Auroras and space weather" page.
The All Points North podcast cast its gaze skywards last autumn, hoping to catch a glimpse of the aurora borealis natural light display, commonly known as the Northern Lights.
In this edition, we hear about the aurora-fuelled boom in tourism in Finnish Lapland, gather tips on how and when to see the lights, and learn about some of the mythology behind the phenomenon.
GPS and power transmission
Most people are not much affected by solar activity and the changes in magnetic fields that cause it.
"Solar activity has a number of effects referred to as 'space weather'. In general, the average person does not notice space weather in daily lives," says Laitinen.
However, during a stronger-than-usual space storm, satellite positioning may be inaccurate or disrupted.
"GPS positioning on mobile phones is generally unaffected by space storms. In radio communications, signals that pass through satellites or are otherwise reflected very far from the atmosphere may be impacted," he explained.
Particles erupting from the Sun carry electric charges that can cause more serious magnetic disturbances on the Earth's surface - in the worst case, they can bring down electricity transmission networks.
Space storms have caused major power outages on a few occasions. For example, in Malmö, Sweden, in 2003, a solar storm left about 50,000 customers without electricity.
In 1989, in Quebec, Canada, a solar storm blacked out an entire province.
"Electrical currents in the atmosphere are regional in scale, ranging from hundreds to thousands of kilometres. But indeed, a powerful solar storm can be observed in some ways all across across the globe," Laitinen points out.
Laitinen doesn't think that the Finnish electricity distribution network, and its transformers, are as vulnerable to disturbances from space weather as the Swedish network.
The design, grounding, and protective switching of the power grid and its transformer stations can prevent solar storm-induced blackouts.
The FMI's space weather service monitors the Sun's activity and, according to Laitinen, it is possible to forecast storms about a day in advance.
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