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  2. Ptolemy's table of chords - Wikipedia

    en.wikipedia.org/wiki/Ptolemy's_table_of_chords

    The table of chords, created by the Greek astronomer, geometer, and geographer Ptolemy in Egypt during the 2nd century AD, is a trigonometric table in Book I, chapter 11 of Ptolemy's Almagest, [1] a treatise on mathematical astronomy. It is essentially equivalent to a table of values of the sine function.

  3. Almagest - Wikipedia

    en.wikipedia.org/wiki/Almagest

    An edition in Latin of the Almagestum in 1515. The Almagest (/ ˈ æ l m ə dʒ ɛ s t / AL-mə-jest) is a 2nd-century mathematical and astronomical treatise on the apparent motions of the stars and planetary paths, written by Claudius Ptolemy (c. AD 100 – c. 170) in Koine Greek. [1]

  4. On Sizes and Distances (Hipparchus) - Wikipedia

    en.wikipedia.org/wiki/On_Sizes_and_Distances...

    In Almagest V, 11, Ptolemy writes: . Now Hipparchus made such an examination principally from the sun. Since from other properties of the sun and moon (of which a study will be made below) it follows that if the distance of one of the two luminaries is given, the distance of the other is also given, he tries by conjecturing the distance of the sun to demonstrate the distance of the moon.

  5. Taylor Swift and Astrology: Every Star Reference in Her Songs ...

    www.aol.com/entertainment/taylor-swift-astrology...

    The track includes the lyrics, “just twin fire signs, four blue eyes,” a nod to her and the element of her zodiac sign (fire Taylor Swift and Astrology: Every Star Reference in Her Songs Explained

  6. Equant - Wikipedia

    en.wikipedia.org/wiki/Equant

    The basic elements of Ptolemaic astronomy, showing a planet on an epicycle (smaller dashed circle), a deferent (larger dashed circle), the eccentric (×) and an equant (•). Equant (or punctum aequans) is a mathematical concept developed by Claudius Ptolemy in the 2nd century AD to account for the observed motion of the planets. The equant is ...

  7. Tetrabiblos - Wikipedia

    en.wikipedia.org/wiki/Tetrabiblos

    Ptolemy states that having dealt with the former subject (astronomy) in its own treatise, he "shall now give an account of the second and less self-sufficient method in a properly philosophical way, so that one whose aim is the truth might never compare its perceptions with the sureness of the first". [27]

  8. Primum Mobile - Wikipedia

    en.wikipedia.org/wiki/Primum_Mobile

    In classical, medieval, and Renaissance astronomy, the Primum Mobile (Latin: "first movable") was the outermost moving sphere in the geocentric model of the universe. [ 1 ] The concept was introduced by Ptolemy to account for the apparent daily motion of the heavens around the Earth, producing the east-to-west rising and setting of the sun and ...

  9. Planisphaerium - Wikipedia

    en.wikipedia.org/wiki/Planisphaerium

    The Planisphaerium is a work by Ptolemy. The title can be translated as "celestial plane" or "star chart". In this work Ptolemy explored the mathematics of mapping figures inscribed in the celestial sphere onto a plane by what is now known as stereographic projection. This method of projection preserves the properties of circles.