One aspect of the moon da Vinci was most concerned with was its apparent glow that acted as a sorce of light after the sunset. At this time, society believed the moon to create its own light source, however, da Vinci realized this was not the case, and observed that Earth reflected the sun's light which was then reflected back from the visible surface of the moon. He called this phenomena "Earthshine" and believed this reflection occured due to the oceans of both the Earth and the moon being such good reflectors of light. He was incorrect on both accounts, however, since light is reflected moreso from the Earth's clouds rather than its oceans, and the moon, as we now know, does not have any oceans. Despite these flaws, his ideas were revolutionary, especially due to the lack of technology da Vinci had available to aid his observations.