1911.] BARNARD— SELF-LUMINOUS NIGHT HAZE. 247 



general star light, perhaps by moisture in the air. This latter con- 

 dition is present as a whitening of the sky, which gives it a " milky " 

 appearance. At other times the sky is more or less feebly luminous, 

 but the luminosity is different from the other condition and is evi- 

 dently not due to a diffusion of star light. In reality the sky seems 

 to be self-luminous. Sometimes the whole sky has this appearance, 

 and at other times a large portion only. At times the illumination 

 is so great that the face of an ordinary watch can be read with no 

 other light than that of the sky. It is indeed seldom that the sky 

 is rich and dark. In any determination of the total amount of the 

 light of the sky the results must be uncertain because of the great 

 changes that so often take place in the amount of the illumination. 

 The self-luminous condition frequently occurs when no ordinary 

 indications of an aurora are present. It is, nevertheless, doubtless 

 of an auroral nature, for Professor Campbell has shown that the 

 spectrum of the aurora is essentially always present on a clear dark 

 night. {Astropliysical Journal. 2, August, 1895, p. 162.) 



I have given an account- of the remarkable pulsating clouds of 

 light that are seen here occasionally and which usually, but not 

 always, have an easterly motion — generally southeast. They are 

 mostly confined to the northern half of the heavens. There is 

 another phenomenon that has been visible on a number of nights of 

 last year, and also in the present year, of which I have seen no 

 record. This consists usually of long strips of diffused luminous 

 haze. I believe that this is really ordinary haze, which for some 

 reason becomes self-luminous. It is not confined to any particular 

 region of the sky nor to any hour of the night. It always has a 

 slow drifting motion among the stars. This motion is comparable 

 wnth that of the ordinary hazy streaky clouds that are often seen in 

 the daytime. They are usually straight and dift'used and as much 

 as 50° or more in length and 3° or 4° or more in width. In some 

 cases they are as bright, or nearly as bright, as the average portions 

 of the Milky Way — that is, they are decidedly noticeable when one's 

 attention is called to them. They apparently are about as transpar- 

 ent as ordinary haze. Sometimes, when seen near the horizon, where 



-Astropliysical Journal. 31, April, 1910, p. 210, etc. 



