Numismatic and History Discussions > History and Archeology

Hipparchos of Nikaia


Dear friends of ancient coins!

"We are dwarfs on the shoulders of giants". This parable is first attested around AD 1120 by Bernard of Chartres, quoted by John of Salisbury in his Metalogicon published around 1159, and used by Isaac Newton, among others. And with Hipparch, one of these giants stands before us!

The coin:
Bithynia, Nikaia, Gallienus, AD 253-268.
AE 25, 5.38g, 25.62mm, 30°
          Bust, draped and cuirassed, seen from behind, wearing radiate crown, r.
          in neck c/m (H in circular incus, (Howgego 821e).
Rev.: NIK - A - IEΩN
          in ex. IΠΠAPX (ΠAP ligated)
         The astronomer Hipparchos in himation seated on a sella l., pointing with his
         right hand to a globe on a slender column.
Ref.: cf. Waddington, Asie Mineure, no. 843 (other dies), pl. 87, fig. 36 (reverse); cf.
         Imhoof-Blumer (1908) no. 6 (other dies)
         Very rare (2 ex. Coin Collection University of Cologne).
The counterstamp probably conceals a declining weight standard. The majority of von Aulock's coins come from a large find at Nicomedia (Howgego).

Hipparchos was born around 190 BC in Nikaia and died around 120 BC on Rhodes. He was the most important Greek astronomer of antiquity and is considered the founder of scientific astronomy based on observations.

Which discoveries and inventions can be traced back to Hipparchos?

(1) He compiled the first star catalogue with 1 028 stars, which was later processed by C. Ptolemy in his Almagest. The catalogue itself has not survived, but in 2012 a palimpsest, the Codex Climaci Rescriptus, was found in the Monastery of St. Catherine on the Sinai Peninsula, which turned out to be part of Hipparch's star catalogue. This enabled Gysemberghh and his working group to reconstruct parts that turned out to be more accurate than those of Ptolemy. Unlike Ptolemy, he used the celestial equator rather than the ecliptic. These lists were still used by Copernicus. The asterisks show that he made his observations from Rhodes. He was also the first to create a scale of star brightnesses.

(2) He could only achieve this accuracy by using new invented devices and methods. Since he had no telescope, according to Gysembergh, he must have used a sighting tube, a so-called dioptre, or already an armillary sphere or a wall quadrant.

(3) Hipparchos introduced the graduation of the circle and used chord tables for his calculations, on which the relationships between angles and lengths were recorded. He thus introduced trigonomy ("chordal calculation") into astronomy and thus became the founder of spherical trigonometry.

(4) With these methods he became the originator of stereographic and orthographic map projection.

(5) When the moon occulted the stars, he was able to determine star positions in the zodiac more precisely. When he compared the star positions he had measured with older data, e.g. those determined by Timarchos and Aristyll about 150 years earlier, he found that they had shifted by 2° in the meantime. This makes him the discoverer of precession. Precession is a property of the earth's movement, whereby the earth's axis shifts in relation to the constellations. Today we know that it is caused by a circular movement of the Earth's rotation. However, this explanation was not accepted at that time. Its exact value is 25850 years. With his observation of 2° in 150 years, he arrived at 27000 years. Not bad!

(6) He calculated the distance and size of the moon and the sun from eclipse observations and determined the first solar and lunar ephemerides. These are tables with the daily positions of the celestial bodies, which could be used by seafarers for navigation.

(7) He found the midpoint equation or Great Inequality, which refers to an irregularity in the moon's motion. It occurs because the moon does not revolve around the earth, but because the earth and moon move around a common centre of gravity, which is located inside the earth due to the mass ratios.

(8) Through astronomical observations he determined the length of the solar year to within 6.5 minutes and established the exact different lengths of the seasons, which he attributed to an eccentric orbit of the sun around the earth.

(9) Hipparchos rejected the heliocentric system of Aristarchos and adhered to the geocentric system. In order to be able to mathematically explain the deviations of the planetary orbits with their retrograde movements, he worked out the eccentric theory of apparent planetary motion, which later led to the epicycle theory.

(10) It was probably under his supervision that the mechanism of Antikythera, a marvel of antiquity, an astronomical computer, was built on Rhodes and found in 1900 in a wreck near the Greek island of Antikythera.

Hipparch's main works are lost. Ptolemy, who knew them, calls him "the greatest lover of truth" and celebrates him as his most important pioneer. He is considered the "Einstein of antiquity". Pliny the Elder, however, called the measuring of the stars a work contrary to God. In particular, he was annoyed that Hipparchos had described a new star, probably a supernova, which violated the eternal symmetry of the celestial sphere. This shows that Hipparchos had taken the side of science in the dispute between religion and science. It was only after the exit from the dark centuries of Christianity that this scientific height could be reached again in the Renaissance.

Pauly writes: Without the retarding scepticism of Hipparchos, the heliocentric system might have been accepted some 1700 years earlier, admittedly to the detriment of science, to which a flash of genius is beneficial, but the strict method based on pedantic data processing and mathematical deduction is indispensable.

(1) The armillary sphere (armilla = bangle, sphaera = sphere) is a further development of the astrolabe. It consists of several metal rings that can be rotated together, forming the shape of a sphere. The imaginary observer is located in the centre of the sphere. If the device depicts the geocentric view of the world, a specific location on Earth is found there.

It remained in use throughout the Middle Ages, mainly in Islamic regions. In Central Europe it only became known again in the 15th century through Regiomontanus and reached its perfection in the 16th century with the Danish astronomer Tycho Brahe.

(2) The wall quadrant is an instrument that can be used to measure exact elevation angles and positions of stars. It consists of a quarter circle with an exact circle division and an associated reading device, a sighting device and a plumb bob. It is firmly mounted on a wall running north-south and exactly perpendicular. This has made it possible that the accuracy could be increased considerably. The most accurate angular quadrant stood on Tycho Brahe's island of Uranienborg and had a radius of 2m.

I have attached:
(1) The pic of a model of Hipparch's celestial globe
The constellations marked, horizontal planes and meridian circle are used to read coordinates or times (Wikiwand).
(2) Renaissance armillary sphere (Wikipedia)
(3) Model of a wall quadrant, Johann Wolfgang Goethe University Frankfurt a. M.

(1) Der Kleine Pauly
(2) American Scientific
(4) Cologne Coin Portal
(5) Wikipedia

Best regards

Your post was a real treat to read Jochen. I have had a life-long interest in science and history, and my two favorite topics in history are ancient history and the history of science.  Your post covers both, in excellent fashion.

Gallienus, as may be surmised by my posting name here, is to me a fascinating and I believe a very under-appreciated historical figure. The wonderful coin you show case in your post is I think a reflection of the intellectual character of Gallienus. In a desperate time of crisis, a coin struck during his reign commemorates an astronomer.


Virgil H:
Fascinating! Thank you, Jochen.



[0] Message Index

Go to full version