The idea of \u200b\u200ba spherical planet would have set out for the first time the Greek philosopher and mathematician Pythagoras of Samos (born on the island of the Aegean Sea, east of the Hellenic peninsula), some A. 500 years C..
Two hundred years later, Aristotle also agreed on the same idea. And he gave some justifications simple: to get away on boats, first let's see the town and then the candles. The stars observed in the sky were different as you travel north or south. Moreover, the shadow of the earth on the moon during lunar eclipses is circular.
With the acceptance of Copernicus' heliocentric model, as we saw, began to consider the idea that our planet spinning on itself, besides making it around the Sun
After the first circumnavigation (Magallanes - Elcano. 1519-1522), the European peoples of the Mediterranean and its northern neighbors just had enough evidence to accept the roundness of the planet and a less vague idea of \u200b\u200bits surface. In contrast, the understanding of ice in the Arctic and Antarctica took much more in different latitudes: the new polar expedition to be held in early twentieth century. From James Cook's arrival to the coast of Tasmania in 1776, the great colonial powers were amazed at the special atmosphere of Oceania. Already
there was no doubt about the approximate shape of the Earth, but new evidence emerged to promote research.
Towards 1660. Newton gave the explanation scientific characteristic that others had assumed. Applying his expertise on circular movements, argued that the Earth's rotation axis with a pole to produce a deformation to swell the planet's equatorial zone.
an experiment carried out in 1851 by French physicist Jean Foucault ended doubts about the reality of Earth rotation. Foucault hung an iron ball about 30cm
diameter and weighing 88kg steel cable over 60m long on the inside of the dome of the Pantheon in Paris. The pendulum finished in a thin edge that barely touched the ground, where he drew a thin line on the sand that had spread on the floor. To prevent vibration of the pendulum when released, he was bound with a rope that was burned, so the pendulum began to swing and, to the wonder of all, as time passed rays were changing position, calculating that to return to the starting position of the pendulum had to spend 31 hours and 47 minutes. If the pendulum was located at the pole, the plane of oscillation would take 24 hours to draw a complete circle, so viewers could watch the Earth "ride" under the pendulum. As for the movements, we know that checking simplest of rotation is given by the alternation of day and night. The translation (ie, the trip around the sun) is verified with the duration of the year.
The inclination of the axis of rotation with respect to the plane of translation around the sun explain the seasons.
Other more complex movements are known due to the periodic variations of the effects of the attraction of the moon and sun, as well as the unequal distribution of land density.
The quest for knowledge that will enable a better understanding of the characteristics of the planet was led by France and Britain. At that time (sixteenth to eighteenth centuries), navigation required good maritime cartography, ie good maps. And the development of complex economies resulted from the Industrial Revolution and colonial policies, promoting the exploration of every corner of the planet. Indeed, it was become clear that there was no "corners" because, at least in principle, the planet was a huge ball.
A new verification of the landform was achieved with the development of the "space race." The first images returned by spacecraft confirmed the known.
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