Ptolemy | |
|---|---|
 Claudius Ptolemy 'the Alexandrian', as depicted in a 16th-century engraving [1] | |
| Born | c. 100 AD[2] Egypt, Roman Empire |
| Died | c. 170 (aged 69–70) AD[2] Alexandria, Egypt, Roman Empire |
| Occupation | |
Claudius Ptolemy (/ˈtɒləmi/; Koinē Greek: Κλαύδιος Πτολεμαῖος, Klaúdios Ptolemaîos, [ˈklaw.di.os pto.lɛˈmɛ.os]; Latin: Claudius Ptolemaeus; c. 100 – c. 170 AD)[2] was a mathematician, astronomer, geographer, and astrologer who wrote about a dozen scientific treatises, three of which were of importance to later Byzantine, Islamic, and Western European science. The first is the astronomical treatise now known as the Almagest, although it was originally entitled the Mathēmatikē Syntaxis (Mathematical Systematic Treatise), and later known as The Greatest Treatise. The second is the Geography, which is a thorough discussion of the geographic knowledge of the Greco-Roman world. The third is the astrological treatise in which he attempted to adapt horoscopic astrology to the Aristotelian natural philosophy of his day. This is sometimes known as the Apotelesmatiká but more commonly known as the Tetrábiblos, from the Koine Greekmeaning "Four Books," or by its Latin equivalent Quadripartitum.
Ptolemy lived in or around the city of Alexandria, in the Roman province of Egypt under Roman rule,[3] had a Latin name (which several historians have taken to imply he was also a Roman citizen),[4] cited Greek philosophers, and used Babylonian observations and Babylonian lunar theory. The 14th-century astronomer Theodore Meliteniotes gave his birthplace as the prominent Greek city Ptolemais Hermiou(Πτολεμαΐς ‘Ερμείου) in the Thebaid (Θηβᾱΐς). This attestation is quite late, however, and there is no evidence to support it.[5] He died in Alexandria around 168.[6]
https://en.wikipedia.org/wiki/Ptolemy
Jiffy can be an informal term for any unspecified short period, as in "I will be back in a jiffy". From this it has acquired a number of more precise applications as the name of multiple units of measurement, each used to express or measure very brief durations of time. First attested in 1780,[1] the word's origin is unclear, though one suggestion is that it was thieves' cant for lightning.[2]
https://en.wikipedia.org/wiki/Jiffy_(time)
The equation of time describes the discrepancy between two kinds of solar time. The word equation is used in the medieval sense of "reconcile a difference". The two times that differ are the apparent solar time, which directly tracks the diurnal motion of the Sun, and mean solar time, which tracks a theoretical mean Sun with uniform motion along the celestial equator. Apparent solar time can be obtained by measurement of the current position (hour angle) of the Sun, as indicated (with limited accuracy) by a sundial. Mean solar time, for the same place, would be the time indicated by a steady clock set so that over the year its differences from apparent solar time would have a mean of zero.[1]
The equation of time is the east or west component of the analemma, a curve representing the angular offset of the Sun from its mean position on the celestial sphere as viewed from Earth. The equation of time values for each day of the year, compiled by astronomical observatories, were widely listed in almanacs and ephemerides.[2][3]:14
https://en.wikipedia.org/wiki/Equation_of_time
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