Peter Linde, an astronomer with Lund University in the south of Sweden, explained to Radio Sweden why the lights are so far south. "There has been a special kind of solar activity, a rather violent exlposion on the solar surface some days ago, which threw away a lot of matter and charged particles and when they hit the earth's magnetic field, they were redirected to the south and the north. In this particular case, it must have been an unusually strong event, so that the resulting Northern Lights also became unusually strong."
The area of high pressure over Sweden in the past week has also made it easier to see the lights. But cloudy weather will move in on Friday, when Sweden will also be in the path of a partial solar eclipse.