(CNN) — 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.

This confluence of the southernmost stretches of the Pacific, Atlantic and Indian Oceans has always been an interesting — and sometimes contentious — spot for oceanographers.

The decision to announce the new ocean coincides with the launch of Planet Possible, National Geographic’s new initiative to inform, inspire and empower people to live more lightly on the planet.

What’s in a name?

Usually, changes to world maps are the result of political changes — for example, Czechoslovakia splitting into the Czech Republic and Slovakia, or Swaziland voting to change its name to Eswatini.

But instead of reflecting a change…