Low-frequency (100 kc./s.) Radio Noise from the Aurora

Abstract

EXTRATERRESTRIAL radio ‘noise’ has been intensively studied during the past decade. The steady background radiation or ‘cosmic noise’ from interstellar space has been observed¹ at frequencies down to about 1 Mc./s. and an intensity of about 10⁻¹⁹ watts per square meter per cycle per second (W.m.⁻² (c./s.)⁻¹). Ellis² later showed that cosmic noise at lower frequencies could not penetrate the earth's magneto-ionic upper atmosphere. Reber³, however, reported observations of steady noise of intensity 10⁻²² W.m.⁻² (c./s.)⁻¹ at frequencies of 520 kc./s. and 140 kc./s. This appeared to be correlated with sidereal time and so was claimed to be cosmic noise.