Claudius Ptolemy (100-170) was an Egyptian astronomer, geographer, mathematician, poet, and astrologer, known for his proposal of the geocentric model of the universe, known as ptolemaic system. He also tried to establish the coordinates of the main places on the planet in terms of latitude and longitude, but his maps were later found to be inaccurate..
His ideas and theories in the field of geography and astronomy had important relevance until the 16th century, when Copernicus demonstrated that the planets revolve around the sun. His work is largely influenced by Hipparchus of Nicaea, a Greek astronomer, geographer, and mathematician..
The great merit of Ptolemy was to synthesize the universe of Greek knowledge in the most representative and complete work of antiquity. It can be said that he was the last and most important scientist of classical antiquity.
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Claudius Ptolemy was born approximately in the year 85 after Christ, although other authors consider that he was born rather in the year 100 after Christ. This doubt persists, since there are not many historical records detailing its early years..
It is estimated that his birthplace was in Upper Egypt, specifically in the city of Ptolemaida Hermia, which was located towards the right side of the Nile River..
This was one of the three cities of Greek origin that could be found in Upper Egypt, the other two were Alexandria and Naucratis.
There is not much biographical information about Ptolemy, however, it can be said that he worked and stayed all his life in Egypt.
Some historical sources indicate that Ptolemy devoted himself to astronomy and astrology mainly. In addition to these tasks, he was also characterized by being an outstanding mathematician and geographer.
One of the most characteristic elements of Ptolemy is that he carried out his studies with an emphasis on empiricism, an approach that he applied in all his works and that differentiated him from other scientists of the time.
Furthermore, many of the descriptions made by Ptolemy were not intended to be exact and real representations of the phenomena he studied; he simply sought to understand and justify why these phenomena occur based on what he observed.
This occurred when trying to explain the theory of epicycles, first introduced by Hipparchus of Nicaea and later expanded by Ptolemy. Through this theory he sought to describe in a geometric way how the movements of the stars were generated.
Hipparchus of Nicaea was a geographer, mathematician, and astronomer who lived between 190 and 120 BC..
No direct data on Hipparchus are known, the information that has transpired has been obtained through the Greek historian and geographer Strabo and from Ptolemy himself..
Ptolemy repeatedly mentioned Hipparchus' advances and achievements, while attributing various inventions to him. One of these was a small telescope that was essential to improve the process of measuring angles, through which it was possible to establish that the period of the solar year lasted 365 days and about 6 hours.
Likewise, the influence of Hipparchus on Ptolemy was also notable thanks to the first publication that the latter produced: Almagest. In the following sections we will detail the characteristics of this momentous work.
During his life, Ptolemy dedicated himself to astronomical observation in the city of Alexandria between the reigns of the emperors Hadrian (from the year 117 to 138) and Antonino Pio (from the year 138 to 171).
Claudius Ptolemy is considered to be part of the so-called second period of the Alexandrian school, which includes the years after the expansion of the Roman Empire.
Although there is no concrete information about it, it is believed that Ptolemy developed his work in the Library of Alexandria. Working within this library, he may have had access to texts by astronomers and geometricians before his time..
If this hypothesis is true, it is considered that Ptolemy was in charge of compiling and systematizing all this knowledge of ancient scientists, framed especially in the field of astronomy, giving meaning to a set of data that could date back to the third century before Christ.
It is also known that Ptolemy did not dedicate himself only to systematize and compile, a work that was already of great importance, but also made relevant contributions in the field of astronomy, specifically regarding the movement of the planets..
At the time when he worked in the library of Alexandria, Ptolemy published the book that became his most emblematic work and his greatest contribution.
This book was named Great mathematical compilation of astronomy. However, today it is better known as Almagest, word that comes from the medieval term almagestum, which in turn derives from the Arabic word al-magisti, whose meaning is "the greatest".
The work that bears the title of Arabic origin corresponds to the first version of this book that reached Western territory.
An outstanding element in Claudius Ptolemy's way of thinking is that he was aware of the importance of making his message understandable to all those who read his works..
He knew that in this way knowledge could reach a greater number of people, regardless of whether or not they had training in the field of mathematics. Furthermore, it was a way to make this knowledge transcend in time.
Therefore, Ptolemy wrote a parallel version of his hypothesis of the movement of the planets, in which he used simpler and more accessible language, directed especially to people not trained in mathematics..
Ptolemy was also characterized by being an outstanding geographer. He designed various maps in which he pointed out the most important points, identifying specific coordinates with longitudes and latitudes.
These maps contained several errors, an understandable fact given the time and the tools available at the time..
In fact, there is information that indicates that Christopher Columbus, the Spanish conqueror, used one of Ptolemy's maps on his travels, and that for this reason he considered it possible to reach India by following the west direction..
Claudius Ptolemy died in the city of Alexandria, sometime around 165 AD.
His main work in the field of astronomy is called Almagest, book that was inspired by the study of Hipparchus of Nicea. In the work, reference is made to the fact that the Earth constitutes the center of the universe and for that reason it remains immobile. Around it revolve the Sun, the Moon and the stars.
Under this assumption all celestial bodies describe perfectly circular orbits..
He dared to project measurements of the Sun, the Moon and a set of celestial bodies that made a total of 1,028 stars.
In ancient times, it was common to think that people's personalities were influenced by the position of the Sun or Moon at the time of birth..
Ptolemy drew up his famous treatise on astrology Tetrabiblis (Four Books), an extensive work on the principles of astrology and horoscopes.
In his theories, he stated that the ailments or diseases that people suffered were due to the influence of the Sun, Moon, stars and planets..
Each celestial body had an influence on certain parts of the human body.
In his work Optics, Ptolemy was the forerunner of research on the law of refraction.
Another of his most influential works is called Geography, work that he completed in view of the fact that Marino de Tiro cannot finish it.
It is a compendium of mathematical techniques for making accurate maps. It compiles different systems of projection and collection of coordinates of the main places of the world that were known.
Although his maps were the precedent for generating more and more precise maps, Ptolemy exaggerated the extent of Asia and Europe..
Paradoxically, years later and based on these maps, Christopher Columbus decided to embark on his journey to India, sailing from east to west, believing that Europe and Asia was the only territory..
Without a doubt, Ptolemy made great contributions to geography, he was one of the forerunners in making maps with coordinates, longitude and latitude. Even though they made big mistakes, they set a precedent for future advances in cartography and earth sciences..
It can be said that it served as a perfector of the methods of map projection and the presentation of the terms "parallel" and "meridian" to draw the imaginary lines of longitude and latitude..
In the field of music, Ptolemy wrote a treatise on music theory called Harmonics. He argued that mathematics influenced both musical systems and celestial bodies (Wikipedia, 2017).
For him, some musical notes came directly from specific planets. He came to think that the distances between the planets and their movements could make the tones of the instruments and music in general vary.
Sundials were also objects of study for Ptolemy. In fact, today we know the artifact called "Ptolemy's socket", an instrument that was used to measure the height of the sun..
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