A strong stream of solar wind on its way to the Earth may spark bright northern lights on Valentine’s Day.
Northern lights, or aurora borealis, are caused when charged particles from the Sun are deflected by the Earth’s magnetic field towards the poles and end up interacting with atoms and molecules in the upper atmosphere.
Earlier this week, the US National Oceanic and Atmospheric Administration flagged the release of a stream of solar wind from a hole in the Sun’s outer corona layer.
The agency predicted a weak disturbance of the Earth's magnetic field on Thursday and Friday by the incoming Coronal Hole High-Speed Stream.
This means auroras could light up the skies in northern Europe and parts of North America on Thursday and Friday.
“Periods of enhanced aurora are possible due to ongoing fast solar winds,” the Met Office said on Wednesday.
“Northern regions [of the UK] have further chances to see the aurora over the next few nights.”
The US agency uses a measure called the Kp index to indicate the level of geomagnetic activity on Earth. The measure, ranging in value from 0 for minimal activity to 9 for extreme geomagnetism, indicates the strength of northern lights.
A value between 0 and 2 suggests a weaker aurora, only visible near the poles, while a Kp of 3 to 5 hints at a “moderate aurora” likely visible further south.
Kp values from 6 to 9 points to the possibility of strong auroras that are visible at much lower latitudes than usual. “The greatest observed three-hour Kp over the past 24 hours was 4,” the agency said.
Between Thursday and Friday, the greatest Kp value is expected to be 4.67, the agency said. This presents the possibility of a weak geomagnetic storm triggering a moderate aurora on Friday.
Relatively clearer skies in northern and western Scotland mean a “much better chance” of spotting auroras there, the Met Office said.
Several space weather events have been observed in recent months as the Sun has neared the peak of its 11-year activity cycle when the number of sunspots, flares, and solar storms increase.
