NASA shares photo of 'Steve' - the mystery purple aurora that rivals the northern lights

Since 2015, a mysterious purple light in the sky has baffled NASA.

The space agency has dubbed the strange light ‘Steve’, but despite having an ordinary name, the light is extremely complex.

Now, NASA has shared a stunning photo of Steve and the Milky Way, snapped over Childs Lake, Canada in 2017.

The beautiful image was shot by photographer Krista Trinder, and has been featured as NASA’s Astronomy Picture of the Day.

NASA said: “What's creating these long glowing streaks in the sky? No one is sure.

Since 2015, a mysterious purple light in the sky has baffled NASA (ESA)

“Known as Strong Thermal Emission Velocity Enhancements (STEVEs), these luminous light-purple sky ribbons may resemble regular auroras, but recent research reveals significant differences.

“A STEVE's great length and unusual colours, when measured precisely, indicate that it may be related to a subauroral ion drift (SAID), a supersonic river of hot atmospheric ions thought previously to be invisible.

There is now an Aurora named... Steve

“Some STEVEs are now also thought to be accompanied by green picket fence structures, a series of sky slats that can appear outside of the main auroral oval that does not involve much glowing nitrogen.”

NASA hopes hope that Steve could help to reveal how processes in Earth's upper atmosphere can have noticeable effects in lower parts of Earth's atmosphere.

This could then provide good insight on how Earth's system works as a whole.