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Hipparchus discovered a method of using the dates of two equinoxes and a solstice to calculate the size and direction of the displacement of the Sun’s orbit. With Hipparchus’s mathematical model, one could calculate not only the Sun’s orbital location on any date, but also its position as seen from Earth. Hipparchus also tried to measure ...
- Life and Work
- Babylonian Sources
- Geometry, Trigonometry and Other Mathematical Techniques
- Lunar and Solar Theory
- Astronomical Instruments and Astrometry
- Star Catalog
- Precession of The Equinoxes
- Geography
- Modern Speculation
- Legacy
Hipparchus was born in Nicaea (Greek Νίκαια), in Bithynia. The exact dates of his life are not known, but Ptolemy attributes astronomical observations to him in the period from 147 to 127 BC, and some of these are stated as made in Rhodes; earlier observations since 162 BC might also have been made by him. His birth date (c.190 BC) was calculated b...
Earlier Greek astronomers and mathematicians were influenced by Babylonian astronomy to some extent, for instance the period relations of the Metonic cycle and Saros cycle may have come from Babylonian sources (see "Babylonian astronomical diaries"). Hipparchus seems to have been the first to exploit Babylonian astronomical knowledge and techniques...
Hipparchus was recognized as the first mathematician known to have possessed a trigonometric table, which he needed when computing the eccentricity of the orbits of the Moon and Sun. He tabulated values for the chord function, which for a central angle in a circle gives the length of the straight line segment between the points where the angle inte...
Motion of the Moon
Hipparchus also studied the motion of the Moon and confirmed the accurate values for two periods of its motion that Chaldean astronomers are widely presumed to have possessed before him, whatever their ultimate origin. The traditional value (from Babylonian System B) for the mean synodic month is 29 days; 31,50,8,20 (sexagesimal) = 29.5305941... days. Expressed as 29 days + 12 hours + 793/1080 hours this value has been used later in the Hebrew calendar. The Chaldeans also knew that 251 synodi...
Orbit of the Moon
It had been known for a long time that the motion of the Moon is not uniform: its speed varies. This is called its anomaly and it repeats with its own period; the anomalistic month. The Chaldeans took account of this arithmetically, and used a table giving the daily motion of the Moon according to the date within a long period. However, the Greeks preferred to think in geometrical models of the sky. At the end of the third century BC, Apollonius of Pergahad proposed two models for lunar and p...
Apparent motion of the Sun
Before Hipparchus, Meton, Euctemon, and their pupils at Athens had made a solstice observation (i.e., timed the moment of the summer solstice) on 27 June 432 BC (proleptic Julian calendar). Aristarchus of Samos is said to have done so in 280 BC, and Hipparchus also had an observation by Archimedes. As shown in a 1991 paper, in 158 BC Hipparchus computed a very erroneous summer solstice from Callippus's calendar. He observed the summer solstice in 146 and 135 BC both accurate to a few hours, b...
Hipparchus and his predecessors used various instruments for astronomical calculations and observations, such as the gnomon, the astrolabe, and the armillary sphere. Hipparchus is credited with the invention or improvement of several astronomical instruments, which were used for a long time for naked-eye observations. According to Synesius of Ptole...
Late in his career (possibly about 135 BC) Hipparchus compiled his star catalog. Scholars have been searching for it for centuries. In 2022, it was announced that a part of it was discovered in a medieval parchment manuscript, Codex Climaci Rescriptus, from Saint Catherine's Monastery in the Sinai Peninsula, Egypt as hidden text (palimpsest). Hippa...
Hipparchus is generally recognized as discoverer of the precession of the equinoxes in 127 BC. His two books on precession, On the Displacement of the Solstitial and Equinoctial Points and On the Length of the Year, are both mentioned in the Almagest of Claudius Ptolemy. According to Ptolemy, Hipparchus measured the longitude of Spica and Regulus a...
Hipparchus's treatise Against the Geography of Eratosthenes in three books is not preserved. Most of our knowledge of it comes from Strabo, according to whom Hipparchus thoroughly and often unfairly criticized Eratosthenes, mainly for internal contradictions and inaccuracy in determining positions of geographical localities. Hipparchus insists that...
Hipparchus was in the international news in 2005, when it was again proposed (as in 1898) that the data on the celestial globe of Hipparchus or in his star catalog may have been preserved in the only surviving large ancient celestial globe which depicts the constellations with moderate accuracy, the globe carried by the Farnese Atlas. There are a v...
He may be depicted opposite Ptolemy in Raphael's 1509–1511 painting The School of Athens, although this figure is usually identified as Zoroaster. The formal name for the ESA's Hipparcos Space Astrometry Mission is High Precision Parallax Collecting Satellite, making a backronym, HiPParCoS, that echoes and commemorates the name of Hipparchus. The l...
Hipparchus (born, Nicaea, Bithynia [now Iznik, Turkey]—died after 127 bce, Rhodes?) was a Greek astronomer and mathematician who made fundamental contributions to the advancement of astronomy as a mathematical science and to the foundations of trigonometry. Although he is commonly ranked among the greatest scientists of antiquity, very little ...
Jul 6, 2023 · This biographical video explores the life of Hipparchus, the Greek astronomer, mathematician, and geographer who is widely considered to be the founder of tr...
- 1 min
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- Code and History
Mar 15, 2022 · Hipparchus of Nicea (l. c. 190 - c. 120 BCE) was a Greek astronomer, geographer, and mathematician regarded as the greatest astronomer of antiquity and one of the greatest of all time. He is best known for his discovery of the precession of the equinoxes and contributed significantly to the field of astronomy on every level.
- Joshua J. Mark
- Hipparchus of Nicea (l. c. 190-c. 120 BCE) was a Greek astronomer, considered one of the greatest astronomers of all time.
- Hipparchus of Nicea is famous for discovering the precession of the equinoxes as well as for major contributions to the field of astronomy. He is a...
- Hipparchus of Nicea is important for his contributions to astronomy, geography, and the invention of astrological instruments. His model of the uni...
- Hipparchus of Nicea is only one contender for the honor of inventing the Antikythera Mechanism. Archimedes of Syracuse is the other major possibility.
Jul 1, 2020 · Hipparchus of Nicaea (c. 190 – c. 120 bc) was an astronomer, geographer, and mathematician. Hipparchus is considered the founder of trigonometry, but is most known for his incidental discovery of the precession of the equinoxes. See the fact file below for more information on the Hipparchus or alternatively, you can download our 24-page ...
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Aug 26, 2016 · Learn about Hipparchus, one of antiquity’s greatest scientists, who measured the earth-moon distance, invented trigonometry, and discovered the precession of the equinoxes. Find out how he used parallax, combinatorics, and star catalogs to advance astronomy and mathematics.
