## Ptolemy – Biography

Ptolemy was a Greek astronomer and geographer who popularized the geocentric theory of the solar system, which lasted for 1400 years. Some argue that he betrayed the ethics of science by doing so.

Koelblen, Un exercice de combinatoire: les relations issues de la figure su00e9cante de Ptolu00e9mu00e9e, in Un parcours en histoire des mathu00e9matiques: travaux et recherches (Nantes, 1993), 1-21. The author’s notes include analysis of errors in Ptolemy’s and Ulugh Beg’s star catalogues.

## What did Ptolemy’s book Almagest focus on?

The Syntaxis was written by Ptolemy as a textbook of mathematical astronomy, explaining geometrical models of the planets based on circle combinations that could be used to predict celestial object motions.

## What ideas did Ptolemy have?

Ptolemy was an astronomer and mathematician who believed that the Earth was at the center of the universe. Because the Greek word for Earth is geo, we call this theory “geocentric.”

## Who is the father of trigonometry?

Hipparchus, a Greek mathematician, created the first known table of chords in around 140 BC; although these tables have not survived, Hipparchus is said to have written twelve books of chord tables, making him the founder of trigonometry.

## Who corrected Ptolemy’s book?

Many Greek ideas, including those put forth by Ptolemy, were contradicted and corrected by Al-Idrisi (around 1099-1180 A.D.). In his book on Geography (1154 A.D.), he corrected the Greek idea that the Indian Ocean was a closed sea, and he also changed the positions of many rivers, including the Danube and the Niger.

## What is Ptolemy most famous for?

Ptolemy made contributions to astronomy, mathematics, geography, musical theory, and optics, compiling a star catalog and the first surviving table of a trigonometric function, as well as mathematically establishing that an object and its mirror image must make equal angles to a mirror.

## What did Ptolemy discover about light?

Ptolemy examined the reflection of light on flat and spherical mirrors, as well as its refraction when it crosses the surface between two transparent media, to support his theory that vision is caused by a flow emanating from the eye.

## What does Ptolemy mean?

Ptolemy definitions: Alexandrian astronomer (second century) who proposed a geocentric system of astronomy that remained unchallenged until the late Renaissance. synonyms: Claudius Ptolemaeus. example of: astronomer, stargazer, uranologist.

## Why was Ptolemy’s model accepted for so long?

Explain why Ptolemy’s model lasted so long: it worked (it could predict planetary positions to within 2u00b0), it was theologically acceptable (the Earth was near the center of all motions), and it accounted for observed planetary motions, retrograde motion, and brightness variations.

## Who first discovered heliocentrism?

Nicolaus Copernicus, known as the “Father of Modern Astronomy,” was a Polish astronomer who proposed the Heliocentric Theory of the Universe, in which the Earth and other planets revolve around the sun.

## Who proved the heliocentric theory?

When Galileo observed four moons in orbit around Jupiter, he discovered evidence to support Copernicus’ heliocentric theory. Beginning on January 7, 1610, he mapped nightly the position of the four “Medicean stars” (later renamed the Galilean moons).

## Who invented trigonometry?

Hipparchus (c. 190u2013120 bce), the first to construct a table of values for a trigonometric function, was the father of modern trigonometry.

## Who invented zero?

In 628, a Hindu astronomer and mathematician named Brahmagupta devised a symbol for the numeral zero: a dot beneath a number. He also devised standard rules for reaching zero through addition and subtraction, as well as the results of operations that include the digit.

## Who invented trigonometry table?

Hipparchus (d. c. 127 bc), a Greek astronomer, was the first to compile a table of trigonometric functions (based on circle chords), which he calculated in 7u00b0 30u2032 increments.