The human being has always had the need to move from one place to another. Sometimes, in search of food, new territories or more benign climates. Others, to extend their commercial activities or seize territories and cities from other humans. Lately, travel for pleasure, on vacation, sightseeing.
Since ancient times, before embarking on a trip, we like to know what we are going to find, what are the forms of the terrain. To represent it, we started with simple strokes that indicated the main features or geographical features of a territory and we have reached the sophisticated current maps.
With the help of the data obtained thanks to the topography it is possible to draw up maps. The main problem consists in having to represent on a flat surface that which is, in reality, on the surface of a sphere. Since ancient times they have made various attempts to solve it.
Currently, topographic projections are used, which consist of transforming topographic data into values on a plane, making small corrections.
To do this, the land area is divided into sections called geographic grids and they are transferred on a plane by means of a coordinate system.
The result is a map in which the coordinates form a grid. The vertical lines are called meridians and each represents a degree of length. The horizontal calls parallel They represent a degree of latitude.
Since the first artificial satellites were launched into space, they have been used to obtain more and more accurate maps of the Earth's surface. From these satellites distances are taken with the help of radio waves and photographs of small sections of the surface are also taken, which must then be joined. For the first time, these methods have allowed to have a real image of the planet.
The whole set of techniques destined to the elaboration of maps of the terrestrial surface receives the name of mapping.
|Magnetism and electricity on Earth|