Vivid night skies lit the plains before the Rockies began

Evidence

The stars were intensely bright, and a well-defined auroral arch, throwing off fantastic coruscations, lighted the whole northern sky. Yet I was only in the Foot Hills, and Long’s glorious Peak was not to be seen. — Isabella L. Bird, A Lady’s Life in the Rocky Mountains, 264

Categorization

• CANDY: A whole northern sky lit by an auroral arch — easy, striking image to hand someone cold.