There are 180 degrees between any two sides of a circle or sphere. The horizontal lines that circle the globe are called Lines of Latitude. Lines of Latitude are known as parallels because they parallel, or run in the same direction as, the Equator. The lines that run between the North and the South Poles are Lines of Longitude, also known as meridians. When it is noon along the Prime Meridian, it is midnight along the International Date Line.
Geographers divide the earth into hemispheres.
Everything north of the equator is in the Northern He misphere, while everything south of the equator is in the Southern Hemisphere. The Western Hemisphere is west of the Prime Meridian, while the Eastern Hemisphere is east of the Prime Meridian. The hemispheres both end at the International Date Line. The United States is in the Northern and Western Hemispheres. We measure the hours of the day by the turning of the earth.