THEMIS Day and Night Layers

"The THEMIS infrared camera imaged the same impact craters in both daytime and nighttime. Infrared images depict the heat materials emit.

Warmer areas appear brighter

and cooler areas darker.

Fine-grained materials like dust

cool quickly after sundown, so

they appear dark in the nighttime

image, while rocky areas cool

slowly and appear lighter. The

extent of rocky material ejected

from the craters can be clearly

mapped. The daytime image

resembles one taken in visible

light, because Sun-facing slopes

are warmer and shaded areas

cooler."

Mars Odyssey, THEMIS
NASA/JPL/Arizona State University image