National Geographic : 1947 Nov
Unlocking Secrets of the Northern Lights 679 U. Wv. uarulel Horseshoe-shaped Drapery Is One Form of Aurora Frequently Seen Draperies are created when bundles of rays lengthen out and form a band, which in turn assumes a curtain like shape (Plate II). The lower border is often more luminous than the other parts. Draperies sometimes seem to move as if blown by a breeze (pages 697, 701, 703). A double drapery like this is rarely seen.