midday
The heavy grass , standing waist-high in the little valley where their ship was at rest , stirred to ripples of vivid green as a light breeze touched it . Above , the sun shone warm upon this world of tropical growth . Harkness , listening in the utter silence for sounds that might mean danger , let his eyes follow up the rugged wall of rock that hemmed them in on two sides . It gleamed with metallic hues in the midday glare . He looked on to the sun above . `` A dark moon ! '' he said wonderingly .