Atlas of Auroral Forms

Following the exceptional displays of aurora that succeeded the long period of low solar activity — referred to as the Maunder Minimum (ca 1620-1716) — scientists tried to categorize auroras according to their structures in an attempt to constitute auroral phenomena as an object of rational inquiry. Agreeing on the fleeting and ever changing appearance of aurora was, however, difficult. The first Auroral Atlas was completed  over two centuries later in 1930 by Norwegian mathematician and astrophysicist Carl Størmer after he — together with Ole Andres Krogness, Norwegian physicist and one of Kristian Birkeland’s assistants (see Hi(s)story)  — developed a faster and more sensitive camera that made it possible to image aurorae (see Posthuman perspective). Størmer took hundreds of photographs of auroras, which allowed him to sort the phenomena into 15 distinct categories. His work was presented in a 15-page atlas with auroral pictures individually produced in a photography laboratory, then glued into the book and covered with translucent silk paper for protection. The atlas draws upon both scientific and artistic sensibility and comprises astronomical, mathematical and photographic expertise. 


Homogeneous Arcs (HA) and Bands (HB)
Auroral Arcs (RA) and Bands (RB) with Ray Structures
Feeble Glows (G):
Auroral Rays (R), Draperies (D) and Coronas (C)
Coronal Aurorae (C)
Spiral Structures
Feeble homogeneous arcs at great altitude (HA*)
Pulsating Arcs (PA) and Pulsating Surfaces (PS)
Cloud-like aurorae, Irregular, Diffuse Patches and Surfaces (DS)
Flaming Aurorae (F)
Red patches
Low-latitude Red Arcs

(Størmer, C., Photographic Atlas of Auroral Forms and Scheme for Visual Observations of Aurorae, 1st ed., A. W. Bröggers Boktrykkeri, Oslo, 1930/1950)

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