Mars Facts  A Martian year is 668 sols (Martian days), 687 Earth days  A Martian day (sol) is 24 hours 37 minutes 22 sec  Atmospheric gaseous components: CO 2 (95%), CO (700ppm), H 2 O (100ppm), N 2, O 2,O 3, NO, H 2, Noble Gases  Major Aerosol Components: Dust, Water Ice  Atmosphere shows annual variation and diurnal variation Pater, I.d.