Carol Laiken, age 12, of Philadelphia, Penna., for her questions

What makes a current in the sea?

The great ocean currents swirl around the mayor oceans north and south of the equator in giant eddies. It is hard to sap where a circling eddy begins and ends, but the big ocean currents are started off by forces operating near the equator. This is the wide waist of the world and the bulge here deflects the prevailing easterly winds and forces them to blow from the northeast above the equator and southeast¬below the equator.

These strong steady breezes blowing toward the equator are the trade winds. They blow the water into steady easterly currents across the world's wide oceans. When these currents meet the land masses they must bend. Above the equator they turn north and below the equator they turn south. Other factors twist them around again until they circle back to rejoin the currents at the equator.