Ptolemy (about 85-165 AD)

Claudius Ptolemaeus Pelusiniensis (Ptolemy) lived in Alexandria, Egypt approximately 85-165 AD or 87-150 AD, and worked there as philosopher, astronomer (and astrologer), mathemetician and geographer. He was of Greek origin. He created a number of monumental and epochal works, above all the Mathematical Syntaxis ("Megale Syntaxas tes Astronomias," Great Syntaxas of Astronomy), which became the foundation of more than a millennium's astronomy, and is better known as Almagest (Ptolemy, ca. 130 AD). This work bound astronomical thinking in the western as well as the arabic world to geocentrism, but also gave positions of the "fixed" stars, and 48 constellations still used today. Other publications include his Geography, an early work of cartography and geography, and the astrological work Tetrabiblos.

Within Almagest, he lists seven nebulous objects, 3 of which are asterisms, but 4 are real deepsky objects; these are all open clusters. Two of them, Praesepe (M44) and the Double Cluster in h and Chi in Perseus, have been taken from Hipparchus, but the other two are new: the Coma Berenices Star Cluster (Mel 111) and "A Nebula behind the Sting of Scorpius", actually open star cluster M7 (now sometimes called Ptolemy's Cluster).

Nebulous objects mentioned in Ptolemy's Almagest:

No.  Description                                         Identification

175  In the right knee [of Cygnus] and 'nubisimilis'     Omega1, Omega2 Cyg
     [cloud-like]
191  At the tip of the right hand [of Perseus] and       h and Chi Per
     nebulous  [or misty]
449  Center of the cloud-shaped convolutions in the      Praesepe (M44)
     breast [of Cancer], called Praesepe
494  Most northerly part of the convolutions which are   15 Com and Mel 111
     called Coma Berenices, between the borders of Leo
     and Ursa Major
567  Following the sting of Scorpius and nebulous        M7
577  In the eye [of Sagittarius]; it is nebulous and     Nu1, Nu2 Sgr
     double
734  Nebulosity in Orion's Head                          Lambda, Phi1, Phi2 Ori

Notes:

Numbers are those in Bailly (1843), here taken from Kenneth Glyn Jones (1968)
No. 567 was identified by Bigourdan as open cluster M7 (NGC 6475), a view is now generally accepted. Previously, Peter and Knobel have identified it with the star Gamma Telescopii (now G Sco) together with 8th-mag globular NGC 6441. The latter view is now rejected because of that globular's faintness.

Honors and such:

Ptolemy's Cluster (Messier 7)
Asteroid (4001) Ptolemaeus
Moon Crater Ptolemaeus
Mars Crater Ptolemaeus

Links:

Ptolemy biographical stuff from the Ptolemy Supper Club
Ptolemy biography from the MacTutor History of Mathematics archive, School of Mathematics and Statistics, University of St. Andrews, Scotland
Ptolemy biography, Sun Education page, High Altitude Observatory
Ptolemäus images, NGC/IC observers page
Some Ptolemy info, Yann Pothier
Asteroid 4001 Ptolemaeus (1949 PV) (NEO/JPL)

References:

Ptolemy, ca. 130 AD. Megale Syntaxas tes Astronomias (Almagest).
Ptolemy's Almagest is available online at Nasa's ADC.
The edition Almagestum (1515) is available online at the University of Vienna.
A translation of Ptolemy's catalog of stars is available online thanks to Brian Tung and the Sternberg Astronomical Institute of Moscow University.
F. Baily, 1843. Description of the Catalogues of Ptolemy, Ulugh Begh, Halley and Hevelius. Mem. roy. astr. Soc., Vol. XIII.
Guillaume Bigourdan, 1892. Observations of 1884. Observations de Nebuleuses et d'amas stellaires [Observations of Nebulae and Star Clusters]. Annales de l'Observatoire de Paris (Observations).
Kenneth Glyn Jones, 1968. The Search for the Nebulae -- I. Journal of the British Astronomical Association, Vol. 78, No. 4 (1968), p. 256-267. Section on Ptolemy: p. 261-263. Reprinted in: The Search for the Nebulae. Chalfont St. Giles, 1975.

[SEDS] | [MAA] | [Home] | [History Home] | [Biographies]

Hartmut Frommert
Christine Kronberg
[contact]