 Some of the charged particles traveling along the Earth's magnetic field lines cause auroras and other geophysical phenomena in the conjugate areas.Other charged particles are reflected back along the magnetic field lines, where they can persist for long periods of time (up to several months or longer), forming artificial radiation belts.According to the "Operation Fishbowl" planning document of November 1961, "Since much valuable data can be obtained from time and spectrum resolved photography, this dictates that the test be performed at nighttime when auroral photographic conditions are best."