<P> The 180th meridian or antimeridian is the meridian 180 ° east or west of the Prime Meridian , with which it forms a great circle dividing the earth into the Western and Eastern Hemispheres . It is common to both east longitude and west longitude . It is used as the basis for the International Date Line because it mostly passes through the open waters of the Pacific Ocean . However , the meridian passes through Russia and Fiji as well as Antarctica . </P>
what is the 180 degree line of longitude called
180th meridian antimeridian