2 October, 2003

Compass and South Magnetic Pole

I am scheduled for Happy Camper School tomorrow but the forecast is for condition 1. If we can we still will go. This is where you receive your safety training in the remote chance you might be stuck out in Antarctica someplace. It is a requirement if you go out into the field.

Today I took a compass outside to check the direction it points. Wow, was that confusing! Perhaps you already know that a compass rarely points true north. It always points to the spot on the earth that is called magnetic north. Inside the earth's molten core there are swirling electric currents. This is similar to taking a wire and coiling it around a nail and plugging it into a battery. These currents make a magnetic field that extends inside and outside the earth. When you place a compass in this field one end of the needle (which is just another magnet) is attracted toward the north and the other end is attracted to the south magnetic pole.

Where I am, the south magnetic pole is almost north of us. Now that really is confusing! It is not near the Earth's South Pole at all. If you were to follow the compass needle to the north you would almost be heading straight to the South Pole. To be precise, you would head 148 degrees east of North. This is called the declination. The needle 'declines' from north by this many degrees. You really have to try it to understand it.

To make matters worse, the swirling molten core keeps moving about and the exact location of the pole changes each year. It has been moving out into the ocean about 800 miles from here. The compass actually dips downward here.

We keep track of direction using GPS sensors and an Argos satellite link. Also, we have an emergency locator beacon that we can track with a handheld unit when we go to pick up our instruments. Using the compass would be a real trick here, and early explorers were quite gifted with these instruments.

This Map blew a bit in the wind so it is not oriented correctly, but maybe you get the idea.

The south magnetic pole is located out in the ocean. At one point it was on the continent.