Great Northern Lights Event: 27-28 May 2017

A masive solar storm (G3 intensity) produced a Kp7 to Kp8 index on 27-28 May 2017. Alerted by Spaceweather.com, I set up to 35mm dSLR cameras (11-16 tokina f/2.8 widefield and Nikkor 35mm f/1.4 lenses). As soon as deep twilight arrived, the aurora was visible, especially a nearly stationary arc over the northwest horizon. Some call this structure "S.T.E.V.E." but I am not exactly sure what it was.

Also: STEVE (Strong Thermal Emission Velocity Enhancement) looks like an aurora, but it is not. The phenomenon is caused by hot (3000°C) ribbons of gas flowing through Earth’s magnetosphere at speeds exceeding 6 km/s (13,000 mph). These ribbons appear during some geomagnetic storms, revealing themselves by their soft purple/mauve glow.

It appeared to rotate and brighten as the arc narrowed. I call this an auronado (auror tornado) for a lack of a better description. After midnight, a green glow on the northern horizon finally brokeout into a substorm with multiple colors and rays around 1:47AM mountain time. Seeing th aurora borealis at 41N is pretty rare, especially with recent streaks of zero sunspots. Anyway, I hope you enjoy this timelapse clip and slides as much as I enjoyed taking them.