Antartica South Pole Challenge. Antarctica is Earth’s southernmost continent forming part of the Southern Hemisphere. It is the world’s fifth largest continent and almost twice the size of Australia and 98% of it is covered by ice and temperatures can reach extremes of 89 degrees centigrade. Antarctica only has two season summer and winter and its surface is a desert and during the summer months is always light and sunny and during winter is always in darkness. It has very little rain and any snow falls tend to remain frozen and builds up over many years into thick sheets of ice in the form of glaciers, ice shelves and icebergs. The Antarctic Circle is marked by the parallel of latitude that runs 66° 33´ 39" (or 66.56083°) south of the Equator and is one of the five major circles of latitude that mark the worlds map. The continent south of this circle is Antarctica, and the zone just to the north of this circle is the Southern Temperate Zone.