a cloud of sodium vapor discharged from a space rocket at a certain point in its trajectory. It is used to facilitate optical observations of the rocket’s flight and to determine the parameters of its trajectory; it is also used for various scientific experiments. The sodium vapor, which is in an atomic state in the artificial comet cloud, intensely disperses sunlight of a certain wavelength, which permits the artificial comet to be observed using light filters even against a comparatively bright background of the sky. Artificial comets were formed during the flights of the first and second Soviet Luna space probes. At a distance of 113,000–150,000 km their brightness corresponded to the fourth-sixth stellar magnitudes. In order to form the artificial comets, the last stage of the launch vehicle was equipped with an evaporation device capable of vaporizing 1 kg of sodium in 5–7 seconds and ejecting the sodium cloud.