Amazing Facts of "The Poles".....

                          The Poles

             

The Earth rotates around an axis, an invisible line passing from one end of the sphere, symmetrically through its center, and out the other end of the North and South poles. The poles exist in three forms-geographic, magnetic, and geomagnetic-each slightly different in location. 

Geographic poles are fixed by the axis of Earth's rotation and  indicated on globes and maps at the congruence of lines of latitude and longitude. Magnetic poles are indicated by compass needles that line up with Earth's magnetic field. Geomagnetic poles are points where the axis of the magnetic field intersects with Earth's surface.

The location of the poles also changes because of the nature of planet Earth. Earth's spin on its axis is not stable; The planet experiences wobbling, a side-to-side motion. Some wobbling, attributable to the flattening of the planet as it rotates, occurs over a 14 month period and is likely reinforced in its momentum by atmospheric and oceanic events. Because of this wobble, the geographic location of the poles moves by some 9 to 18 feet. Another wobble is probably caused by a yearly highpressure weather system that settles over Siberia and unbalances the Earth, creating a wobble of  about 9 feet. 

Yet another kind of wobble probably emanates from gravity pulling on the Earth's inner core. Earth's wobble, the changes in geomagnetic fields, and the rotation of the inner core all seem to be tied together in ways that are not fully understood. Nevertheless, they make the poles hard to pinpoint.

• What is Geomagnetism?

Scientists believe that Earth's magnetism arises from electric currents generated by the movement of hot liquid iron in its core. The currents create a magnetic field invisible lines of force flowing between Earth's geomagnetic poles. These sre not the same  as the North and South poles and, more significant, they are not stationary. The geomagnetic poles mark the ends of the axis of Earth's magnetic field.

In 1971 a group of scientists investigating a 30,000-year-old aboriginal campsite in australia discovered that the fire's heat had allowed iron particles in the stones to realign with earth's magnetic field at the time. What's more, the iron particles pointed south, indicating that magnetic north at that time must have been somewhere in the antarctic. The discovery confirmed other recent reversals of the Earth's Magnetic field.

It is now understood that major reversals in Earth's magnetic field occur about every half million years. Shorter flips, lasting a few thousand to 200,000 years, occur at other times. These reversals are clearly recorded in the rocks created in the seafloor's Mid-Atlantic Ridge, which are carried away from the ridge by shifting ocean-floor plates.

Earth's magnetic field dominates a region called the magnestosphere, which wraps around the planet and the atmosphere.

Solar wind-charged particles flowing from the sun-presses the magnetosphere against Earth on the side facing the sun and stretches it on the shadow side.

Nevertheless,some particles of solar wind do leak through and are trapped in the van Allen belts. When they hit atoms of gas in the upper atmosphere near the geomagnetic poles, they produce the eerie light display's that are called auroras.

• Robert Peary / Arctic Explorer

A career naval officer, Robert Edwin peary (1856-1920) had a passion for Arctic exploration. In1891 he accepted an American flag from the president of the fledgling National Geographic Society, who told him to ''place it as far north on this planet as you possibly can!''peary made four tries for the pole. In 1909, with his African sledger Matthew Henson, four Eskimos, and 40 dogs, he left base camp on northern Ellesmere Island and reported reaching the pole on April 6, where he  spent 30 hours of study and photography. peary was an instant hero, but his achievement evoked skepticism. Investigators ultimately concluded that peary got within 60 miles of the North pole.