The Aurora of March 30

Abstract

ON the night of March 30 there occurred here an exceptionally brilliant auroral display, remarkable, in this latitude, in several respects. When I saw it I was a few miles north of the city proper, and the southern horizon was lit up by the lights in town, so that any faint display near the horizon to the south would have been obscured. I first noticed the aurora about 8.30 p.m. (75th meridian east of Greenwich time), and it continued till midnight, but was much fainter and confined to a simple glow in the north-west to north-east after about ten o'clock. When first noticed, the sky from east to west round by north was either quite deep red or reddish white. No clouds were then visible, and there were no streamers, though the glow extended about to the zenith. Then, as the red grew fainter, a few small clouds formed in the north, and the still glow was confined to the sky from east to west along the horizon, and about 50° above it in the north, but less in the east and west. From this arch of light, streamers shot up, not only from the north but from east and west (or east by south and west by south), and met in a place about 10° south of the zenith. These streamers pulsated rapidly, the light at times starting at the arch of (apparently) still glow and travelling without break to the point of meeting. At other times the glow would appear in places along the course of the former streamers—first near the arch, then further on, disappearing again, to again appear nearer the zenith. When these rays met in the place south of the zenith, their paths sometimes crossed, but more generally the rays seemed to mingle and either form a roundish glowing spot about 5° to 10° across, or a roundish, confused mass of glow that looked like glowing smoke. Occasionally an appearance like a hollow-centred whirlpool appeared. When the rays met without mingling, one ray seemed to cut another off abruptly, only one ray ever appearing to pass the point of meeting. About nine o'clock, rays could be faintly seen in the south extending up to the point of meeting. Then these rays grew brighter, extending from about 30° above the southern horizon, and throbbing up from there to the place near the zenith where the northern, eastern, and western rays met. The southern rays were fainter than the others. They may have extended further towards the horizon than 30° above it, but, if they did, the lower part of them was too faint to be seen, on account of the city lights. I have never before seen or heard of an aurora in this latitude, with rays coming upwards from the south. The whole display seems to have been much farther south than usual. It was also much brighter than is usually seen here, even on exceptional occasions.