Over the heads of many in Ireland and the UK last night, strong solar weather activity created an abnormally large aurora borealis effect in one of the phenomenon’s most southerly advances in many years.
Due to the speeds at which solar radiation erupts and travels towards our planet, the Irish aurora was only forecast yesterday (Wednesday, 7 October) by the Space Weather Prediction Center, part of the US National Oceanic and Atmospheric Administration (NOAA).
The active aurora phenomenon occurs when a dense wave of solar material – typically a high-speed stream of solar wind or a large cloud that exploded off the sun called a coronal mass ejection – hits Earth’s magnetic field, causing it to ‘rattle’. This is what manifests in the colourful showpiece that is usually only viewable in the Scandinavian and Arctic regions.
This rattling of the solar wind causes electrons to fall towards the planet’s poles, creating the dazzling light show.
— Ian Carruthers (@HurricanesArt) October 8, 2015
— Niall O’Donovan (@niallodonovan) October 8, 2015
— Ken Cox (@coxcom15) October 7, 2015
— Tyler Collins (@tylerc0llins) October 7, 2015
Coincidentally, on the same day the aurora stunned onlookers here, NASA has also revealed findings on what causes another aurora phenomenon – pulsating aurora – which, until now, while known about on a basic level, was still largely mysterious.
A research team connected with the US space agency says that, thanks to a lucky conjunction of two satellites, a ground-based array of all-sky cameras, and some spectacular aurora borealis, researchers have uncovered evidence of the unexpected role that electrons play in creating the dancing auroras.
Until now, low-energy electrons were thought to have little or no effect on the speed or changing shape of a pulsating aurora, but, based on the new findings, these secondary particles – which are the result of the initial shockwave hitting the atmosphere – are shooting back into space, which is what causes the flickering.
“It turns out that secondary electrons could very well be a big piece of the puzzle to how, why, and when the energy that creates auroras is transferred to the upper atmosphere,” said Marilia Samara, lead author of the study.
This means that all previous model calculations will have to be re-written, as they did not take the electron activity into account.