Millions of children around the world have grown up memorizing basic facts about geography: there are seven continents and four oceans. Until now. National Geographic, one of the world’s pre-eminent and most visible mapmaking groups, has officially decreed the existence of a fifth ocean. Called the Southern Ocean, it’s the body of water that surrounds Antarctica. Usually, changes to world maps are the result of political changes — the Fifth Ocean is a rare example of a mapmaker making an effort to alter the planet.