What are the main tools for geographical orientation? Summary and explanation of the cardinal points and the compass.
Geographical orientation
There are four cardinal points: East (orient or levante), West ( ovest or ponente), North (sttentrione or tramontana) and South (middle or ostro).
To orient oneself, one can take into consideration the apparent diurnal motion of the Sun. This system is however approximate since the sun rises exactly in the East and sets exactly in the West only on the equinox days. In spring-summer it is moved towards the North, in autumn-winter towards the South.
The apparent excursion of the Sun between the two tropics is useful for orientation. In the northern temperate zone we can identify the South by the position of the Sun at the height of its arc (noon). In the southern temperate zone we will identify the North.
At night we can orient ourselves by looking at the North Star which is almost at the North Celestial Pole. The projection on the plane of vision that goes from our eyes to the Star indicates the north. For the southern hemisphere, the direction of the south is given by Octantis in the constellation of octans.
The compass
The use of the compass allows orientation in any situation. It is a magnetized needle free to rotate in a horizontal plane. The needle is placed along the meridian of the place indicating the North with the blackened tip and the South with the other. The direction of the needle does not coincide exactly with the direction of the meridian but forms an angle called magnetic declination . To obtain a precise orientation it is necessary to know the value of the angle.
The declination is due to the fact that the magnetic poles do not coincide with the geographic poles. The North Pole is located in one of the Queen Elizabeth Islands while the South Pole is in Adélie Land in Antarctica. They are not diametrically opposed and are zones of variable extension that change their position over time.
The cardinal points
With the cardinal points you can give a first indication of the position of a place. Therefore, in addition to the four cardinal points, there are four other intermediate ones:
- North East (Greek)
- South East (sirocco)
- South West (southwest)
- North West (master)
Among these, eight more are inserted, then sixteen until reaching the 32 of the compass rose . The exact position of a point on the horizon is obtained by determining the azimuth and the distance of the point, that is, the polar coordinates. The azimuth is the angle between the meridian line and the direction of the point, measured from North and proceeding clockwise. The distance is the linear measurement between the station point and the point considered.
