The mystery of a beautiful aurora called ‘STEVE’ has finally been solved

A picture of STEVE spurting across the sky (Provider: Krista Trinder)

It’s the incredible celestial wonder with a distinctly Earth-bound name.

Now scientists think they’ve cracked the mystery of STEVE – an aurora-like phenomenon which causes thin ribbons of pink, mauve and green light to appear in the sky.

It was named after amateur astronomers spotted a ‘glowing ribbon of purple light’ in the night sky and hailed it a new type of aurora, a natural phenomenon that’s often called the Northern Lights.

The stargazers then christened their discovery STEVE, which stands for ‘Strong Thermal Emission Velocity Enhancement’.

STEVE isn’t actually a proper aurora, even though he looks like one, because his glow is not entirely caused by charged particles raining down from space into Earth’s upper atmosphere.

Last year, scientists said STEVE was a ‘sky-glow’ which can sometimes appear during magnetic storms sparked by the sun.

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But a new study has just been published which once again crowns STEVE as an aurora, although he’s a different type from the `stunning Northern Lights.

It concludes that STEVE has a split personality driven by two different processes.

The ‘reddish arc’ is caused by heating of charged particles in the atmosphere, whilst the green ‘picket fence’ streaks are more like normal auroras.

‘Aurora is defined by particle precipitation, electrons and protons actually falling into our atmosphere, whereas the STEVE atmospheric glow comes from heating without particle precipitation,’ said Bea Gallardo-Lacourt, a space physicist at the University of Calgary and co-author of the new study.

‘The precipitating electrons that cause the green picket fence are thus aurora, though this occurs outside the auroral zone, so it’s indeed unique.’


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