The Light Hemisphere, along with the Dark Hemisphere, make up the two halves of Eternia.
In the 2002 series, it was established that the Light and Dark Hemispheres were created when Hordak and his sorcerers used an artifact called the triad to cast the spell of separation. Hordak used the spell to separate the planet into two hemispheres, light and dark. However, the planet itself, began to separate and, realizing he was in jeopardy, Hordak ceased the spell and sent the three parts of the Triad to the corners of Eternia.