The Nightglow Spectrum: II. H Radiation in the Night Sky

Abstract

A narrow H α emission line has been found in two nightglow spectra obtained in the tropics. The mean apparent emission rates are 10.8 Rayleighs in the first half of the night and 8.1 Rayleighs in the second. When corrected for the H α emission of galactic origin a component remains which is considered to originate from within the solar system and whose emission rates are 6.0 R and 4.2 R respectively. The low value of the ratio (1.43) of these latter two emission rates is shown to favour a geocentric rather than a heliocentric distribution of neutral hydrogen, and one in which the density falls off as the inverse first power of the geocentric distance as far as about 10 Earth radii.