Aurora australis has lit up skies across southern Australia after an “extreme” geomagnetic solar storm.
Brightly coloured skies were visible in Victoria, South Australia, Tasmania, and New Zealand.
So what IS “Aurora australis” ? This is from the University of Tasmania: “Outer space is filled with electrically charged particles. When they hit the Earth’s atmosphere, they can make it light up like a fluorescent light tube. This tends to happen in the polar regions, where Earth’s magnetic field is trapping the charge.
There’s a stream of protons and electrons from the sun moving past the Earth at several hundred kilometres per second. When electrons encounter the Earth’s magnetic field, they become trapped, moving along the field lines to the poles. The magnetic field funnels the electrons into the atmosphere in the polar regions and they strike atoms of oxygen or nitrogen molecules.
In the low-density upper atmosphere, the atoms only lose this energy by emitting light, which creates the glow you see. Green and red come from oxygen at different altitudes, and violet comes from nitrogen. There’s light in other colours as well, but the atomic physics and the eye’s sensitivity mean that red, green and violet are the colours we can see.”
(source: https://www.utas.edu.au/about/news-and-stories/articles/2023/aurora-australis-in-a-nutshell)
The Guardian Australia article
