National Geographic : 1978 Sep
Ninety North: All directions point south from Uemura's triumphal camp site at the North Pole, shown here (above) in a panorama of pictures. From this exceptional vantage point, the sun can be seen circling the horizon, not setting for six months, and then giving way to six months of twilight and night. The Pole itself has no length or width or breadth. It is a mathematical point where the imaginary line of the earth's axis intersects the earth's sur face. Since no plaques or markers exist here on this desert of moving ice, Ue mura relied on celestial navigation with his sextant (right)to determine the loca tion of the Pole. On this day, as on all the days of his journey, his position was monitored by satellite. A transmitter attached to his sled beamed regular radio signals to Nimbus 6, a United States meteorologi cal research satellite, passing over the Pole every 108 minutes. Data collected from the signals were relayed by a tracking station in Alaska to the God dard Space Flight Center in Maryland, where latitude and longitude, as well as temperature and atmospheric pres sure, were computed automatically.