Polar ice caps grow and shrinking with the seasons. Winds re-distribute dust seasonally. Active sand dunes are present. Dust storms are seen as yellow clouds. Streaks on the surface show wind directions.
Areas covered with dust are bright .
Both are irregular, not spherical. May be similar to carbonaceous chondrites. The upper atmosphere lacks ozone and other UV absorbers Chemical composition of the atmosphere is similar to that of Venus , but the atmospheric pressure is much less. No liquid water exists because the atmospheric pressure is too low. Circulation Atmospheric circulation is similar to that of Earth.