Max Moorman wrote to EarthSky:
Faint purple aurora borealis, green airglow, and the Milky Way over lights at a dock near Granite, Colorado.
Tech specs for those interested: 3-row panoramic image comprised of 21 twenty-second exposures @ f/2.8 & ISO 6400. Sony ?7s, Sigma 24-35 @ 24mm. Stitched in Microsoft ICE, finished in Adobe Camera Raw & Photoshop CC.