Meet Steve, the winter sky phenomenon
Steve has been around for eons, but has been mis-identified as aurora until now
Kate Ravilious
@katerav
Tue 31 Dec 2019 16.30 EST
Hands up if youve ever seen Steve. No, not the chap living down the road, but Steve the winter sky phenomenon. First spotted by auroral photographers in 2016, Steve is a purple band of light, sometimes accompanied by green lines, nicknamed picket-fences.
Although Steve shares similarities with auroras the glowing coloured lights visible from high latitudes during winter months latest research shows that Steve is something quite different. Analysing photos of Steve taken from different locations, and using the stars in the background as markers, scientists have shown that Steve sits at between 130km and 270km altitude, while the picket fence is between 95km and 150km.
Compared with conventional auroras, Steve has a wider range of wavelengths, is longer and thinner, doesnt hang around for as long and appears in areas further south than a typical aurora.
Auroras are formed by charged particles disturbing Earths magnetic field, but Steves distinctly different shape and behaviour suggests that his origins lie in some unusual chemistry involving very hot ionised gas. Its likely Steve has been around for eons, but mis-identified as aurora until now. Most of us are unlikely to see him, but thankfully he has now been captured on film Chasing Steve.
More:
https://www.theguardian.com/science/2019/dec/31/meet-steve-the-winter-sky-phenomenon