EntityQ426943· pop 8· linked from 4 articlesLunar XSign in to saveclair-obscur effect in which light and shadow creates the appearance of a letter 'X' on the rim of the Blanchinus, La Caille and Purbach cratersConnectionsMoonConceptNASAConceptInternational Standard Book NumberEntityCambridge University PressEntitychiaroscuroEntityterminatorEntityGoogle Lunar X PrizeEntityAstronomy Picture of the DayEntityPurbachEntityBlanchinusEntityLa CailleEntityUkertEntityCategoriesOrbit of the Moon