The genesis of Hippachus' celestial globe

TL;DR

This study analyzes Hipparchus' celestial globe, comparing ancient astronomical data, and presents a virtual 3D reconstruction, revealing influences from Babylonian astronomy and clarifying its relationship with Ptolemy's data.

Contribution

It offers a new analysis of Hipparchus' star catalogue data, highlighting Babylonian influences and providing a virtual 3D model of his celestial globe.

Findings

Hipparchus' data is correlated with Ptolemy's but not simply copied.

Babylonian influences on Hipparchus' astronomy are evident but not definitively proven.

A virtual 3D model of Hipparchus' celestial globe is presented.

Abstract

This paper summarises briefly and in English some of the results of the book Hoffmann: Hipparchs Himmelsglobus, Springer, 2017 that had to be written in German. The globe of Hipparchus is not preserved. For that reason, it has been a source of much speculation and scientific inquiry during the last few centuries. This study presents a new analysis of the data given in the commentary on Aratus' poem by Hipparchus, in comparison with other contemporary Babylonian and Greek astronomical data, as well as their predecessors in the first millennium and their successors up to Ptolemy. The result of all these studies are the following: i) although the data of Ptolemy and Hipparchus are undoubtedly correlated, it is certainly also wrong to accuse Ptolemy having simply copied and transformed it without correct citation; ii) although Hipparchus presumably observed most of his star catalogue with his own instruments, we cannot neglect Babylonian influences. Hipparchus was educated in Greek astronomy but, in his time, there are traces of Babylonian influences since at least two centuries. Since we are unable to definitely prove that Hipparchus used Babylonian data, we are not sure if there are direct Babylonian influences in his time or as a consequence of his education only. Finally, we present a virtual 3D-image showing what the globe of Hipparchus might have looked like.