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).

Ptolemy's work was widely and longly used by the educated community. In particular, his Almagest was used (and verified) by many consecutive observers, notably Al Sufi (903-986 AD) and Ulugh Begh (1394-1449). Bigourdan (1892) has compiled a list including the positions of the nebulous objects presumably observed by Ptolemy and successors, see this list sorted by observer.

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

Honors and such:

Links: References:

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

Hartmut Frommert
Christine Kronberg