In order to know the meaning of the term sphere it is necessary, first, to discover its etymological origin. In this case, we can underline that it is a word that derives from the Greek, specifically "sphaira", which means "sphere."
The concept is used in the geometry to name a body which is limited by a curved surface whose points are equidistant from center .
It is a revolution surface composed of points equidistant from the mentioned center . The union of the spherical surface and the interior constitutes the sphere in question. As a solid of revolution, the sphere is formed by rotating a semicircle around its diameter.
The properties of the spheres indicate that all of its flat sections are circles . The sections that pass through the center are major circles , while those that do not cross the center are minor circles .
In the same way, we cannot ignore the existence of what is known as the armillary sphere. Specifically, under that term is an instrument that was used since ancient times within the scope of what is astronomy. Specifically, it was used to determine the position of the different celestial bodies. However, over time it also began to be used in the field of navigation.
From this device we can highlight another important series of features, among which we can especially highlight the following:
-An armillary sphere is represented on the flag of Portugal. Specifically, it is the yellow part that is responsible for protecting the shield and is included in the flag because it comes to act as a "wink" to the period of the fifteenth century in which important discoveries were made by Portuguese navigators.
-If it is called armillary, it is because it is composed of several rings or armillary. Specifically, among those we can highlight the one that is responsible for representing both the meridian and what the horizon is.
-It is unknown who or who were the creators of this article for astronomy, although it is known that its origins are found in Ancient Greece.
In the field of watchmaking , the circle in which the clockwise hands move is called a sphere. The earth sphere or earthy , on the other hand, is the planet land . To the ideal sphere in which the stars appear in an apparent way on the land it's called celestial sphere .
There are other uses of the notion that are symbolic. To the ambit or the context where an individual or an entity exerts influence or acts, it is known as a sphere. For example: “I never liked the sphere of politics”, "Don't worry, Jorge is a trustworthy man who has been in my sphere for many years.", “The tertiary academies that work in the province belong to the sphere of the Ministry of Education of the Nation”.