Como encontrar o norte verdadeiro

Suppose you have decided to travel to the North Pole. You can not take a plane there. So you take the compass from his pocket, observe the needle swing northward and traces a path, right? Wrong. To reach the North Pole or true north, just below the compass needle will not work.

If you want to go from a point at the lower end of a map to a point at the upper end, you need to follow the true north. True North is represented on maps and globes by lines of geographical direction longitude . Every line of longitude begins and ends at the poles of the Earth and is the direct route north and south.

Earth anatomy
The conventions of cartography help people immediately understand a map

Compasses, on the other hand, lead you to the magnetic north (in English), a point in the Arctic regions of Canada that constantly changes place based on the activity of the magnetic fields of Earth . The iron fluid in the center of the planet acts as a large magnet, creating a relatively weak magnetic field. The strength of this magnetic field has a horizontal component in the direction of magnetic north. The needle of a compass is magnetized and freely suspended to allow the direct horizontal force to magnetic north.

But the magnet of the Earth is not perfectly aligned with the geographic poles. For this reason, there is a difference between true north on a map and north indicated by a compass. This difference is called magnetic declination and is measured by the angle between true north and magnetic north when plotted on a map.

The magnetic declination will vary from place to place, depending on the intensity of the magnetic field of the earth. For example, if you hold a compass in New Zealand, magnetic north is about 20 degrees east of true north, while the declination in Los Angeles will be the 12th. Geographical lines exist where true north and magnetic north are aligned, and are called agonic lines . In North America cross the peninsula of Florida to the Great Lakes and the Arctic Ocean .

Given these irregularities, as you arrive at the North Pole or true north in a destination? Continue reading to discover how you can do this - at any time of day and with natural and artificial navigation tools.

Interesting historical points

  • First century - Chinese invent the compass.
  • 720 AD - The Chinese recognize the existence of the magnetic declination.
  • Century 12 - the technology compass comes to Europe.
  • 1520 - George Hartman measures the magnetic declination.
  • 1700 - Edmund Halley is the first known map of magnetic declination in the world.
  • 1851 - the magnetic north pole is discovered. [Source: Geological Survey of Canada]


Teste seus conhecimentos sobre: