A Photoelectric Study of the Light from the Night Sky
Abstract
Observations of the light from the night sky have been made with a recording photoelectric photometer. Records covering the entire hemisphere were made in about one hour. Observations were obtained at different hours of the night and at different seasons of the year, in order to determine the distribution of the various sources of radiation coming from the night sky. Observations of certain regions of the sky were reduced by analytical methods to evaluate the unknowns. All of the tracings, however, were reduced by a graphical method, in which all radiations having similar distributions over the sky were grouped with respect to their co-ordinate systems. Isophotes have been constructed for the zodiacal light, arranging the observations into four groups. There is a seasonal variation in the zodiacal light which might be in- terpreted as resulting from a cloud of meteoric particles which are in conjunction with the sun during the late winter months. An analysis of the light associated with the galactic system shows that after the effect of the stars has been removed there is an excess of light, which we shall call the galactic light, and which is probably produced by the scattering of starlight by in- terstellar matter. It also includes the galactic nebulae. The mean amount of galactic light at latitude ~0 is equal to 57 stars of the tenth photographic magnitude, or is equivalent to 5.6 mag. per square degree. Applying a theoretical discussion of scattering by Struve, it is found that the spheri- cal albedo is probably large and that in the galactic plane the medium is opaque
- Publication:
-
The Astrophysical Journal
- Pub Date:
- April 1937
- DOI:
- 10.1086/143815
- Bibcode:
- 1937ApJ....85..213E