The art of identifying our location and pointing into the right direction to reach our destination has been practiced for several thousands of years. Celestial navigation guided Egyptians and Greeks in ancient history, and its practice is commonly cited in Latin and Greek literature. Since then, new inventions have joined the panoply of tools that provide positioning information, from the astrolabe and compass to the GPS.
Hipparchus, a Hellenist, invented the astrolabe in 150 B.C. This tool measures angles from a circular star chart and derives distance to the stars and planets above the line of the horizon. This device was improved over centuries with contributions from several cultures and was still in use in the mid-1400s.
Claudius Ptolemaeus, born in Egypt in 90 AD, used his mathematical and astronomy knowledge to create the quadrant that measures the altitude above the horizon. This was originally intended to be an improvement upon the astrolabe but soon became an adjunct way to improve the accuracy of positioning.
China is credited for developing the compass and discovering that a magnetic needle will point to the north. Zheng He, born in China in 1402 and admiral of the Chinese fleet, appears in the literature as the first sailor to use the compass for sailing guidance. Richard Norwood, an English mathematician, took this invention to the next level in 1576 by placing the needle in free suspension and measuring the angle of the needle from the plane of the Earth (magnetic dip). This invention still operates in air navigation to compensation for speed and turn effects on identifying the position.
Octant and Sextant
Isaac Newton (1643-1727), John Hadley (1682-1744 and Thomas Godfrey (1704-1749) share the spotlight for the invention of the octant, which brought the art of navigational guidance to a higher level of accuracy. The device introduces mirrors to visually superimpose a direct view of the horizon with another distant object. The angle between the two points maps over a 45-degree arc device. The sextant evolved the platform by enlarging the arc to a 60-degree arc.
The 20th century brought a series of electronic navigation solutions. Radio broadcasts supported chronometer alignments, radio beacons provided wireless anchors from which to navigate, and echo sounders map envelops of the surroundings. Observations from A. Hoyt Taylor and Leo C. Young led to radar technology that was first deployed on board the USS Leary in April 1937.
Credit for developing the GPS belongs to a large group of scientists. Some controversy arose as to who invented the idea of using satellites orbiting the Earth to triangulate the position of a receiver. The National Inventors Hall of Fame inducted U.S. Air Force Col. Brad Parkinson for the invention of the GPS. Ivan Getting from the Department of Defense is named as the inventor of the GPS. Roger Easton was honored with the National Medal of Technology from the president of the United States in 2004 for visionary work and pioneering activities with the NAVSTAR-GPS. Thanks to them, GPS has entered the consumer market and is integrated into cell phones and cars.
- Photo Credit sailing image by Francisco Nogueira from Fotolia.com stars on sky image by Marek Kosmal from Fotolia.com compass image by cico from Fotolia.com sextant image by serge simo from Fotolia.com antennes bateau image by Marc Rigaud from Fotolia.com communications satellite image by Paul Moore from Fotolia.com
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