The Aurora Borealis

Abstract

THERE was a brilliant display of aurora borealis visible from this place on Sunday the 9th inst. I first noticed it about 10.45 P.M.; there was then a considerable luminosity in the N. W. with a magnificent red glow and streamers springing from the W. extending to within 20° of the eastern horizon, also radiation from other parts in the N. and N. W., but less brilliant. At about 10.55 P.M., a bright streamer made its appearance near the zenith crossing the red at right angles, and standing out clearly upon it. The aurora had nearly faded away at 11.10. When it was at its brightest through a direct-vision spectroscope with the slit rather wide and directed to the N. W., where there was scarcely any colour, the red and green bands usually seen under such circumstances were clearly defined, more particularly the red band. I then directed the spectroscope to the W., at a part where the red light was most intense, to my surprise the red band was scarcely to be discerned, and looked blurred, and spread out towards the green, which was better defined, but not clearly so. I several times repeated the observation with the same result. This, if confirmed by other observations, would appear to point to some fluorescent property of the upper atmosphere.