Raymond Roberts, age 16, of Arlington Heights, I11., for his question:
WHERE EXACTLY ARE THE NORTH AND SOUTH POLES?
This problem is not as simple as it seems. There are five different poles in the Arctic and five matching poles in the Antarctic. Each region has a geographic pole, a magnetic pole, a geomagnetic pole, an instantaneous pole and a pole of balance. What's more, all of them are moving at different rates and in different directions.
The most familiar poles are the geographic poles that pinpoint the extreme north and south spots on the globe. Here the lines of longitude come together. The north geographic pole is under the Arctic ocean, and for most of the year it is covered with drifting packs of ice. If you mark the exact spot with a flag, the shifting ice soon moves it out of position.
The south geographic pole is in Antarctica, high on a glacial plateau. Since 1956 the exact spot has been marked by the Amundsen‑Scott Station, a settlement of U.S.,researchers.
These poles mark the limits of north and south according to the geographic lines of latitude and longitude. Both are 90 degrees from the equator.
The instantaneous poles mark the opposite ends of the axis around which the earth rotates. Since she axis has a slight wobble, they move in circles that vary in width from a foot to about 70 feet. These are the chandler circles, and it takes about 14 months to go around once.
The poles of balance mark the exact centers of the two chandler circles. They should mark the geographic poles, but slight changes occur. Since 1900 the north pole of balance has moved six inches toward North America and the south pole of balance has moved six inches toward Australia.
The magnetic poles mark the two ends of the mighty magnet inside the earth. They are large oval areas, some distance from the geographic poles. The north magnetic pole is in Canada, near Bathurst Island. The south magnetic pole is on the shoreline of Antarctica. Both these poles wander several miles a year. The geomagnetic poles mark the points where the outer magnetic field points down to the earth. One is in Greenland; the other is 900 miles north of the south geographic pole.
All the poles make minor motions related to the wobbly axis and the shifting magnetic field. We now know that the earth's crust slides around, causing them to glide around on enormous global tours. For example, 500 million years ago the North Pole was near Hawaii and the South Pole was out in the Atlantic Ocean.