Claudius Ptolemy

Claudius Ptolemy (or Ptolemy). He is one of the most important figures in the history of Astronomy . He was an Egyptian astronomer and geographer. He proposed the geocentric system as the basis of celestial mechanics that lasted for more than 1400 years. His astronomical theories and explanations dominated scientific thought until the 16th century .

Summary

[ disguise ]

• 1 Biographical summary
  • 1 Contributions
  • 2 Death
• 2 Publications
• 3 Sources

Biographical summary

He was born in Egypt approximately in the year 85 , although very little is known about him, it can be said that he was the last important scientist of antiquity.

Contributions

Although he owes his fame to the exposition of his Ptolemaic system, his knowledge went much further; He compiled the scientific knowledge of his time, to which he added his observations and those of Hipparchus of Nicaea , and formed 13 volumes that summarize five hundred years of Greek astronomy and that dominated Western astronomical thought for the following fourteen centuries. This work reached Europe in a version translated into Arabic, and is known as Almagest (Ptolemy had called it Mathematical Syntax).

The central theme of Almagest is the explanation of the Ptolemaic system. According to this system, the Earth is located in the center of the Universe and the sun, the moon and the planets revolve around it dragged by a large sphere called “primum movile”, while the Earth is spherical and stationary. The stars are located in fixed positions on the surface of said sphere.

Also, and according to Ptolemy’s theory, the Sun, the Moon and the planets are also endowed with additional proper movements that are added to that of the primun movile. Ptolemy states that the planets describe circular orbits called epicycles around central points that in turn orbit eccentrically around the Earth.

Therefore, all celestial bodies describe perfectly circular orbits, although the apparent trajectories are justified by eccentricities. Furthermore, in this work he offered the measurements of the sun and the moon and a catalog of 1,028 stars.

The Ptolemaic theory is unsustainable because it is based on the adoption of false assumptions; However, it is coherent with itself from a mathematical point of view. Despite everything, his astronomical work had great influence in the Middle Ages, being compared to that of Aristotle in philosophy.

Death

He died in Alexandria in the year 165 .

Publications

He published tables derived from the theories of the Almagest but independently called Hand Tables which are only known from written references. He also took it upon himself to write and publish his Planetary Hypothesis in simple language to reduce the need for mathematical training of his readers.

One of his greatest works was Geography , where he made maps of the known world giving coordinates to the most important places with latitude and longitude, which of course, contained serious errors; It is said that this work was what led Columbus to believe that he could reach the Indies from the west, since they seemed to be closer there.

In this way, despite all the errors that Claudius Ptolemy made in his work, he was one of the Astronomers who changed the vision of the universe and tried to scientifically explain the mechanics of the stars.

The fact that his mistaken theory has persisted for so long does not depend on himself, but on the mainly religious communities that found themselves very comfortable with the geocentric theory and the compatibility with their beliefs.