This region of lower albedo appears as a dark feature in the reported photograph. This impact caused the temporary evaporation ot the sol H2SO4 particles of the upper haze layer and, consequently, a decrease of the albedo of the region around the point of entrance of the comet in the Venusian cloud layers. We propose that this event was actually the impact of a small (~1010 gr) comet-like object, consisting mainly of water, on Venus. After eliminating the possibilities of a film defect and an interference from an artificial Earth satellite or an interplanetary object, we conclude that this feature was the signature of an event that took place on the upper haze layer of the Venusian atmosphere. In this paper we report on a photographic evidence of a short duration dark feature on Venus, which was observed on. The lack of observational evidence of cometary impacts is usually attributed either to the rarity of such events or to the fact that presently their observational signature is not well understood. The main candidate water sources are: (a) outgassing from the Venusian surface, due to volcanic activity and (b) cometary impacts. The present small amount of water in the atmosphere of Venus, in connection with the estimated short time scale of water loss from this planet, has lead to the hypothesis that the water concentration in the Venusian atmosphere is in a dynamical equilibrium, where the losses are counter-balanced by a suitable water source.

Cambridge photographic moon atlas