The Aurora of January 31; Position of Auroral Rays

Abstract

THE bright loop shown in G. F. Seabroke's drawings of the aurora on January 31 at 6.30 and 6.35 p.m., as seen at Rugby, remind me of a striking feature seen here. If it was the same, a comparison of the observations will give some idea of the height of the phenomenon. As seen here at about 6.241/2 this feature was the most conspicuous part of the aurora; it was a somewhat pear-shaped bright patch, with a region along the middle of it not quite so bright. Its edge was 10° above the moon, at Venus, Jupiter, β and η Pegasi; its pointed end being low down, and a good deal further to the right. At 6.261/2 Venus was in the midst of its left end, and Jupiter quite outside. The moon was 5° below the lower edge. The dusky region gradually darkened, and finally opened through the right end of the patch, which became united by a rather serpentine bright band to a somewhat similar, but partly red, bright patch rising up in the east-north-east. This bright band formed the southern border of the aurora. At 6.311/2 the position of the central line of this band, including the western bright patch which now formed a loop in it open to the north, was about as follows:—At or near the moon, one-third of the way from η Ceti to Venus, ζ Cygni (the junction of the patch with the new band), α Pegasi I think, β Trianguli, α Tauri, and below Procyon.