Accretion of matter from the solar nebula eventually formed the earth. The different atmospheres and ocean were probably created as a result of the volcanic outgassing that initially occurred on earth.
Conversely, for every time zone boundary you cross going east, you add one hour. Because Earth is round, if you continue to travel in one direction, you will eventually return to your starting point, and you would have set your watch forward or backward a full day.
C. Differing levels of pre- and post- natal care
