Science Question of the Week

This week's question comes from Isabel of Nightingale Elementary School in Chicago. Isabel and her teacher, Martha Roldan, ask:

How many oceans are on the Earth?

Isabel

Almost all of us (at least folks of my age) were taught in school that there are four oceans on our planet: the Atlantic, Pacific, Indian and Arctic Oceans. Recently the scientists who study the Earth's oceans agreed that there is really a fifth ocean which they named the Southern Ocean (called by others the Antarctic Ocean). This ocean circles the Antarctic continent and on average extends out to a latitude of about 60^oS. The map shows the location of the Sourthern Ocean.

Image courtesy CIA Factbook

If you look at a globe of the Earth, you might wonder why scientists decided there is another ocean circling the icy mass of the Antarctic continent. After all, it seems that everything is ocean in that part of the world, so how can you separate one ocean from another? The answer comes from the fact that there are powerful currents in the oceans, and the currents that surround Antarctica form a sort of natural barrier between the waters of the Southern Ocean and the other oceans of the world.

In 2000, the International Hydrographic Organization (IHO) voted to recognize the Soutern Ocean as the fifth ocean of the Earth. The Southern Ocean is smaller than the Pacific, Atlantic and Indian Oceans, but larger than the Arctic. Unlike the other oceans, its boundaries are with other oceans and not with landmasses.

Thank you for writing, Isabel!

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