So-called cracks in the Earth’s magnetic field have led to spectacular aurora light shows being seen in the skies, despite there not having been a solar storm to generate them.
According to spaceweather.com, this is called the Russell-McPherron effect, with cracks in the magnetic field letting more solar wind pass through during the equinoxes, i.e. during the spring and fall equinoxes, where both the day and night are the same length.
“The Rusell-McPherron effect is more of a geometrical effect to do with the orientation of the solar wind’s magnetic field and that of the Earth. There is always a cusp or open region of the Earth’s magnetic field around the north and south poles so the ‘cracks’ are permanent,” explained Ciaran Beggan, a geophysicist from the British Geological Survey.