Regulated by the shadow exerted by the sun
Target: Geometric shapes in defensive structures
Tourist route: Romanesque route of Penafiel
The route of the Romanesque is located in the valleys of the rivers Sousa, Douro and Tâmega, in a vast territory that includes, among others, the town of Penafiel.
In the route of the Romanesque is possible to contemplate a varied set of patrimony: monasteries, churches, chapels, castles, towers, bridges and memorials. However, in the town of Penafiel is also possible to find a significant set of sundials placed in churches and monasteries or private houses, with more or less protagonism, better or worse preserved, carved in granite, marble or slate, it adopts various forms (circular, rectangular, biface, bulging). These instruments of measuring time, enrich the patrimony of this region.
The first Kepler's law states that the planets describe elliptical orbits with the sun at one focus.
In effect, ellipse is a curve on a plan surrounding two focal points such as the sum of the distances to the two focal points is constant for every point on the curve.
However, the discovery of the ellipse, as well as the parabola and or hyperbola, are associated with the search for solutions to problems that were not solved only by using the non-graduated ruler and the compass.
The first flat articulated systems arise with the Greeks in the fifth century BC in order to solve some problems, as cube doubling, angle trisection, which are insoluble using only the non-graduated ruler and the compass. Among these articulated systems arise the ellipsographs that, as the name suggests, allow to trace ellipses.
