The earth has been arbitrarily divided into longitudinal sections, with the starting point (0) meridian going through Greenwich England.
The lines of longitude converge at two points: the poles.
That is the reference point/dividing line, and if you travel from England to America, you are travelling to and in the West. At 180° is the International Date Line. Once you pass that while westbound, you are in the East until you reach Greenwich again.
Eastern Antarctica is the area between our imaginary lines of 0° and 180°. Western Antarctica is the area between our imaginary lines of 180° and 360°/0°.
Clear as mud, right?
LOL And I got that EXACTLY reversed: 0 to 180 is WEST, 180 to 360/0 is EAST. AARGH!